Somewhere I have the wiring schematic that I use, which involves a SPDT push button or momentary toggle for the uncoupler and a DPDT momentary toggle for the unloader. I'll try to remember to dig it out and post it. The trick is you do not want the magnet to be energized when unloading, and it may overheat. Thus, 2 simple buttons cannot be used.
EDIT: Found it. Copy attached.