ORIGINAL: StikDude
I wanted to use up some old 2 wire switches so I just plugged the battery into an extra servo slot, and put the bind plug in where the battery/bind connector is. Did the binding, turned off the switch removed the bind plug and reconnected the battery and was good to go. Took about 2 mins. to do. You only need the 3 wire switch if you want to bind through the switch hardness. Try it, it will work and get you by until your switch arrives.
That's the way I do it, and about every other guy I know that has converted existing planes over from 72MHz to Spektrum 2.4GHz systems. No need to replace the existing switches in you planes. If you have an electric plane (using an ESC with BEC to power the RX), you just do it this way as well, since you don't have a switch harness or an RX batt pack.