umm taking off the backcap would be better, cause it gives it a bit more momentum. You can try using Guitrum's method below, but I've never tried it, so it's at your own risk. All my true gel bodies are rubbed off by nail polish remover, so yeah I have no idea.
heres a note concerning G1 tips: you have to thicken up the 'flat' area of the tip with tape until its the same width of the cap, then tape it on the cap, then put your grips on the cap, over the tape. you can also use blu-tak to stick the tips on (and to add weight). and david, dont double post lol.
Just a suggestion @BloorA: Maybe you want to re-edit your Introduction to Pen Modding and post it? i think it might be useful to beginners in pen modding.
oh my! You just reminded me of that lol I completely forgot lol XP Thanks I'll post it up when I'm done.. I might have deleted it so I'm going to rewrite it heh