Not really hard to install at all, aside from the fact that where it's located is pretty tight. From what I remember, there are two nuts that thread onto the switch itself and mount it in the bracket. As for getting it, local junkyard or a Honda Dealership would be the two best bets. You could try a parts store like Advance or Pep Boys but they likely don't have it in stock. If you go the junkyard route, I'm pretty sure that any 88-91 civic or crx would work for the part, unless there is a difference that I don't know about between the auto and manual versions. I'll check with my roommate tonight and see what he can come up with since he works at a Honda Dealer.

Forgot about the what kind of switch is it, it is a push button style, actually more like a plunger style as there is a large white piece that sticks out towards the brake pedal arm and when the pedal is depressed it releases the plunger and makes the connection for the brake light. You could likely rig something up but it would be real hard to find a switch large enough to fit the hole and actually stay in the same position while driving and such.