I discussed this a bit in the Rigs of Doom thread, and wound up settling for a stereo pedal. I've got both a Roland RE-20 and an EHX Stereo Memory Man w/ Hazarai. Both are solid choices, but anything with a stereo output should do it. Radial also makes a neat pedal, but I can't recall the name.
All that being said, a cheap ABY should work, but you could always modify it if need be?