For those of you who want to depot but are afraid of burning plastic, fumes etc, check out the following links!
Heating: http://swap.beverlys.net/heat.html OR http://www.specktra.net/depotting.php
Dental Floss: http://www.makeupalley.com/user/notepad/olivia142_2
You can also use your hairdryer, in a similar way to the iron.. just blast it over the back of the insert. It does take quite awhile, though.