The pedals are obviously hooked up mechanically with cable runs, but I'd venture they're connected to some sort of a patchbay in that rack that is electronically controlled with relays, and that in turn receives information about what loops to turn on from the actual floor controller, which is probably basically a MIDI or similar controller with memory slots. Custom work all the way probably anyway, but also likely can be made by tweaking and combining factory-made stuff.
Neil Young also has a similar hookup thingy that allows mixing and matching his pedals, but I don't recall if his has a memory and several modes...