My new P2k has cable housing that is way too long. I'd like to take it apart and cut the housing but I'm worried about how to put the cables back in the frame. Dan's review of building up a new P2k mentioned how hard it was to put the grommets in the first time, but does not mention how hard it might be once the bike is built up.

Does anyone have experience taking out and replacing the cables on an existing bike? Will I need any special tools? When I push the cable into the front of the frame, how do I get it out of the correct hole in the back of the frame? Do I need to pull a thread back when I remove a cable so that I can use the thread to pull the cable back?