How to boot a G3 iMac without the video boards connected?

[Makosuke]

I kind of have a feeling this belongs in the Apple Collectors section, but anyway:

For no particularly good reason, I'm attempting to frankenmac an old G3 iMac (333 tray-load) into a compact little box, sans monitor et al.

I've managed to dismantle it completely without electrocuting myself or breaking anything (apparent). I took the motherboard/drive chunk and hooked it to the power supply board, then plugged in the little board that has the power button, and hooked up an external monitor.

However, when I plug it in and push the button, I get nothing--not so much as a twitch.

It's entirely possible it's just broken, but I'm thinking maybe it's refusing to power on without the analog board and/or monitor unit attached. I could plug them in easily enough to test, but being that those are the high voltage parts I'd rather not if it's not necessary.

Anybody tried this, and if so is there something simple to jumper?

There were, at one time, tutorials for this all over the place, but I can't seem to find any good ones after a fair amount of Googling, and the few I can find are all for the newer slot-loaders.