I think it was on the wiki... lemme check... Yup, look in the "design files" section, the part about "Tip Manager and Bed Manager".
If you need a general idea, the PDF file (PCB production prints) could be enough.
If you want the exact electric schema, go for the PCB artist files, but I have no idea if you can still find that software around.
Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.
