Cutting the throttle cable can be a pain in the ass, but here are some tips I've learned in the past (probably from people like don-ohio...)
Only do this if it's one of those, "slide the cable into the thing and then screw the screw to the cable, holding it in place" deals... if it has one of those fat cylinders on top that you need, don't do it yourself unless you can weld or something.
1.) When cutting the cable, wrap it in electrical tape. Then, cut the cable in the middle of the electrical tape. This will make the wires not fray all over the place and make it a million times easier to put into the slide to screw back in.
2.) Put the throttle at full, slide the cable in, then close the throttle... at the point where you set the screw, make a mark, and cut it to just before that mark so you have a little extra.
3.) Be really careful not to screw up... hahaha ;)