I picked up the parts of the last week or so, but the idea had been in my head for a while. We had no working doorbells at the front or back, and wanted that anyway, so we picked up a kit with one wireless button, picked up two extra buttons, and a reed switch.
Testing was easy, as the reed switch came in a package with screw terminals on it. The switch has both NO(normally open) and NC(normally closed) terminals on it, so I could use whatever was needed.
A quick gutting of the doorbell button showed that it was just using a simple tac switch. Connecting some wires up temporarily to the same spots and testing showed the idea was solid(using the NO part of the reed switch).
A solder sucker and iron were used to remove the switch, leaving the through holes empty and well within my basic soldering skills. The reed switch was extracted, wires bent to match the holes and soldered in. Tested with the magnet a few more times and all was good.
Finally I removed the bell housing to see about installing it, and if you look at the pictures you can see how this will not work. I didn't have as much room as I pictured, and I was unable to modify the circuit board enough(with my skills at least) to get it to fit.
For now I'm leaving this as a fail, but if I figure out a way to get it working, I'm all up for that.