The existing switches are cheap flimsy pads of bent metal that deform under pressure to make contact with the pads underneath:

You can see the unused Sleep switch - obviously the same board is used in more expensive models with extra options. I like toggle switches. Specifically, for this mod, momentary toggle switches, that return to centre when you let go. They have a great clunky look and feel.

Each switch has, obviously enough, an active pole and a ground. The ground is common to all switches. I decided, for this hack, to tap the solder pads on the switch board, rather than removing the board and splicing into the ribbon cable. That makes life a little harder to start with, but means I have access to the original switches for testing and troubleshooting. So step one is tap the ground, and run it to a bus for the new switches. I decided to install headers for the switches, rather than hardwire the switches, because that's the modular way to do it :)

By using headers, again, there's a little extra work initially, but I can add and alter switches more easily later. I have double throw toggle switches, so each new switch has an "up" and a "down" that are different, giving me, in effect, 2 switches per chassis. So I can replace the original 6 buttons with 3 switches - Alarm snooze/alarm off, Time set/Alarm set, and Hour/Minute. After attaching them, it occured to me that really, Alarm Off should be a Big Red Switch, and snooze probably something similarly easy to find and press. So right away the headers have paid for themselves, although not as much as thinking through the off switch to start with.... That's that, really. The switches all work, no major issues in hooking them up. On to stage 2!