OK, seems I've figured this thing out. The screws were so small they didn't look like screws even with the magnifying glass and the wires weren't going in the side... but that's what it was!
As for the wiring, what I found was that the RH/RC power for respective transformers on the old therm (prev jumped for use with only one transformer) is now simply the red power wire to Totaline's R. Don't seem to need the blue common to power the receiver, so I'm hoping it handles that itself.
It's running and I'm not even going to test the cooling system now :)
Hope this helps someone else :)