[captainslug]

All that's needed to watercool the MOSfet heatspreader is a ball-end milled channel or two along the side opposite the mosfets. Then use a torch to silver solder a length or two of 1/4" OD copper tubing into the channel(s). Or just skip the milled channel and sloppily solder the tubes on after flattening them a little.

You can then use instant-tube fittings on its ends to connect it to a pump, reservoir, and radiator.

I wouldn't recommend trying to add cross-drilled channels inside the heat spreader since you don't want to mix aluminum and copper in a water-cooling loop. Doing that would lead to galvanic corrosion unless your coolant mixture isn't atleast 40% antifreeze.
There's also just not much space inside the heat spreader to add them anyways without having to replace the through-bolt holes with shorter tapped holes.

Does anyone have a mechanical drawing of the heat spreader or any information on the hole spacings on it? I could work up a printable machining template for the wiki if I simply have some measurements to work from.