haha Nick! learn from my mistakes!
yea at this point i say fuck a fag. i dont doubt that they are designed to handle the heat of a running engine cause... um... they are meant to be put in engines. and ive installed them successfully in a few engines and they go for miles and miles. but when i pound bearings on i like to make very liberal use of me MAPP gas torch and the plastic just makes it too touchy to deal with. so all metal ZKLs all the way for me.
that being said dont go too crazy with the torch, even with all metal ZKLs or similar. an oven is better i guess (SLOW) so you probably should use that. just dont let direct flame sit on the balls too much or you'll scorch em. really about 7ish solid seconds of flame exposure to the inner race keeps the bearings alive and gets em hot enough that they will just about drop all the way home. little oil, a hammer, and a seatpost and you have 100% successfully driven bearings every time.