Hair dryer is the safest way to do it at home.
Heres instructions for skates but it is the same idea. I did mine in the oven but I would NOT recommend this as it is easy to melt the liner if you don't do it correctly.
1. We recommend using a hand-held hair dryer for heat molding, because it will not heat the entire boot, causing it to lose its shape.
2. Work on one part of the boot at a time.
3. Leave the shell on your boot. This will help to prevent the boot from distorting when it is heated.
4. Since you are not heating your boots in the oven, you can leave the shell on.
5. VERY IMPORTANT: Loosen the laces on the boots, and spread both sides of the (boot) as far apart as you can. Pull the tongue out of the boot all the way. You want hot air to flow freely out of the boot, so the hair dryer will not overheat and shut down.
6. Set the hair dryer to high heat, and place it inside the boot, pointing in the direction of the area you want to modify. (High heat has worked for people using these instructions in the past, with hair dryers ranging from 1200 to 1500 watts. Use caution with higher wattage hair dryers).
7. Turn the hair dryer on, and set a timer for 10 minutes.
8. Leave the hair dryer and the boot alone for 10 minutes. (Many skate manufacturers will tell you to keep the hair dryer moving, and to heat both the inside and the outside of the boot. This part of the process may depend on what you are trying to accomplish. Follow your boot maker's instructions.)
1. While you are waiting for the boots to heat, prepare your feet for the molding process:
2. If you need to push the boot away from your foot, use Mole Foam to build up a padded layer on the part of your foot that is feeling pressure from the boot (Mole Foam is a Dr. Scholl product similar to Mole Skin, but it is thicker, because it has a layer of foam).
9. Prepare your foot for (boarding), the way you normally do. If you usually wrap your foot with athletic tape before you skate, do it now too. Wear the same socks you normally wear to (board).
10. After your boot has heated for 10 minutes, quickly put it on your prepared foot, and lace and tie the boot as tight as you possibly can, without damaging the boot or your foot.
11. Stand firmly in your boot until it has completely cooled. Some people like to speed up the cooling process by applying an ice pack to the warm part of the boot (a bag of frozen peas or corn will also work nicely for this).
12. You may need to heat mold your boots more than once to get the best fit, because heated boots cool rather quickly. Remold the boots as many times as necessary to make them fit well and feel comfortable on your feet.