Installing Therm-ic Classic or Perform heated insoles. (These have the heating elements pre-installed into the toes).

Tip: Do this at room temperature or warmer. The first one will take you about 30 - 45 minutes. The second one will go much faster as you already know what to do.

Basic tools needed:
A pencil,  a solid pointed sharp knife, sharp sturdy scissors, electrical tape our duct tape.

Tip: Do one boot at a time so you don't confuse right and left parts.

Step 1- Unbuckle your boot and pull out your liner. Then open your liner and remove your insole, heel first. Tip: Some insoles are hard to get a hold onto. Reach inside and along the arch. You should be able to put your fingers between the insole and liner at the arch.
Step 2- Put your original insole on top of the Therm-ic insole. Line up the insoles from the toes and from the arch side.
Step 3- Mark with a pencil where to trim the Therm-ic insole. Marks should be at the heel and outside of foot. Tip: If you have the Perform insoles, you may only need to trim the outside of the insole as the Perform insole come in sizes.
Step 4- Trim the Therm-ic insoles with the sharp scissors. Tip: Keep in mind; it's better to trim a little at a time. You can always trim more but you can't add material. After you trim the insole, slide it in your liner to see if it fits properly. If not, you'll need to trim more until it fits a little snug. If you took too much off, you can order more insoles.
Step 5- Remove any ruff spots where you trimmed. Finish off trim job with a belt sander if possible.
Step 6- Place the wire that comes from the toes, down the bottom of the Therm-ic insole so the wire comes out by the heel. Tape the wire to the bottom of the insole so it lays flat and stays in place.
Step 7- Cut a slit in the heel of your liner with the knife. The slit will be where the wire passes through the liner. Start with a small slit and make it larger as you need. Tip: Some boots already have a slit which will make your job easier. To test the size of the slit, put the male end of the plug through the slit from the outside of your liner. If it fits from the outside going in, chances are it will fit from the inside going out.
Step 8- Install the trimmed insole into the liner, but only put in about half way. Take the male plug from the end of the wire and put it inside your liner and through the slit. Pull the male plug out the liner and allow the wire to tack up slack. As you take up slack, slide the heel of the Therm-ic insole into the boot. Be careful not to crease the wires.
Step 9- Place the wire up the back of your liner so it comes out by the top. Tape the wire flat against the liner in 2 or 3 places. Tip: Some boots already have elastic holders for the wires which will make your job easier.
Step 10- With care, slide your liner back into your boot. Tip: Place your boot on a bench or table and have someone hold the boot open while you insert your liner.
Step 11- Clip your battery so the clip is between the shell and liner. Plug in the wire and turn on to test.
Step 12- Repeat the steps for other boot.

Therm-ic Perform installation
 

Installing the Therm-ic Trimfit system. (The heating elements are used with your current insoles.)

Tip: Do this at room temperature or warmer. The first one will take you about 45 minutes. The second one will go much faster as you already know what to do.

Basic tools needed:
A pencil, a solid pointed sharp knife, sharp scissors, electrical tape our duct tape.

Tip: Do one boot at a time so you don't confuse right and left parts.

Step 1- Unbuckle your boot and pull out your liner. Then open your liner and remove your insole, heel first. Tip: Your insoles may be hard to get a hold onto. Reach inside and along the arch. You should be able to put your fingers between the insole and liner at the arch.
Step 2- Place the Therm-ic heating element on top of your insole, wires facing down towards your insoles, pointed side towards the toes. The heating element should be located slightly behind the toes but ahead of the ball of your foot.
Step 3- Mark with a pencil on your insole where to make a hole to put the wire through so the wire comes out the underside of your insole while the heating element lays on top flat. 
Step 4- Make a hole with the knife (a drill may be needed for stiff insoles) large enough to put the wire through. The hole will be covered by the heating element. Tip: Keep in mind; it's better to start with a small hole and make larger as needed. You can always make the hole larger but you can't make it smaller.
Step 5- Place the wire from the heating element through the hole and down the bottom of your insole so the wire comes out by the heel. Make sure the heating element is laying flat on your insole. Tape the wire to the bottom of the insole so it lays flat and stays in place. Tip: You may run the wire along the arch side of the insole if it interferes with the bottom of your insole.
Step 6- Take the correct (right or left) Cambrelle overlay, remove the adhesive backing and place on top your insole. Trim the excess with the scissors and smooth the edges. The Cambrelle overlay is designed to keep the heating element in place and protect it so your socks don't catch it when sliding your foot in and out of the boot.
Step 7- Cut a slit in the heel of your liner with the knife. The slit will be where the wire passes through the liner. Start with a small slit and make it larger as you need. Tip: Some boots already have a slit which will make your job easier. To test the size of the slit, put the male end of the plug through the slit from the outside of your liner. If it fits from the outside going in, chances are it will fit from the inside going out.
Step 8- Install your insole into the liner, but only put in about half way. Take the male plug from the end of the wire and put it inside your liner and through the slit. Pull the male plug out the liner and allow the wire to tack up slack. As you take up slack, slide the heel of your insole into the boot. Be careful not to crease the wires.
Step 9- Place the wire up the back of your liner so it comes out by the top. Tape the wire flat against the liner in 2 or 3 places. Tip: Some boots already have elastic holders for the wires which will make your job easier.
Step 10- With care, slide your liner back into your boot. Tip: Place your boot on a bench or table and have someone hold the boot open while you insert your liner.
Step 11- Clip your battery so the clip is between the shell and liner. Plug in the wire and turn on to test.
Step 12- Repeat the steps for other boot.

Therm-ic Trimfit installation

Tips on use:
1- Caution; Don't brag to your friends about your warm feet on the slopes when they have cold feet. This may cause them to throw a snowball at you.
2- Do not wear thick socks as this will insulate you from the heat.
3- Only turn on the power when your feet are cold. If you're feet are not cold, turn the power off to save the batteries.
4- Remember to turn off your batteries when you go in for a break or lunch.