You don't have to take the wheel off, and you don't need a hook tool. It'd help, I'm sure, but I replaced one of mine in a Target parking lot with nothing more than a small pocket knife and a piece of napkin. I was waiting for Target to open, had the switch, figured why not go for it.
If you go to Rite Aid / Walgreens / any pharmacy place and look for dental tools, you should be able to find something that looks like what the dentist uses to scrap plaque off when you get a cleaning. You could probably use that. Otherwise, if you want to go my route, just take a slim blade...maybe a nail file would be good too. Use something like a folded napkin or a matchbook cover to cover the blade and protect the leather when you pry the switch out. It's about an inch deep, I think there's a lip on the inside edge to grab. Once you get it part way out, you can grab it and wiggle it the rest of the way. There's not a lot of slack in the wire, but there's enough to be able to swap out switches.
Seriously - if a monkey like me could do it in 10 minutes with improvised tools, I think anyone can do it.
