I would just need to make a thin gap for the wires and a larger hole for the switch.

Could someone with no real experience do this? And what kind of tools should I use?
What type of guitar?
If you want to put the killswitch under the pickguard (if any) all you'll need is a drill press and/ or a router. Using either a drill press, router or dremel (use the dremel only if you own one and neither of the other tools, i wouldn't recommend going out and buying one because there cheaper than the other 2 tools, its not nearly as powerful) make a hole in your guitar big enough for the switch and then using a router, dremel (dremel is acceptable for this) or drill press (drill a whole heap of little holes) route a thin line for the wires to get to the control cavity. There you go!
Pretty Simple

I have a Strat, and I'm gonna put it around the area where Tom Morello has his on his Strat. I don't believe I have any of those so that's one other thing I'll have to buy...