I bought a used dual oven, which has 6 wires coming out of it. Unfortunately, it didn't come with a manual, and even the online installation instructions aren't much help. (The manual, as well as the tag on the oven, only refer to "3-wire"...)
Model: Kitchen Aid YKEBS277WB-0
The only manual I've found is here.
Pictures of the wires, and where they end up (including the tech sheet that was inside the oven) are available here.
I tried calling Kitchen Aid, but they were of no help ("oven is too old"...)
I hooked up red->L1, black->L2, white->neutral, green->ground, and the upper oven worked, but not the lower one. (I wasn't quite sure what to do with blue & yellow.)