You know I never thought to look, or if I did don't remember. Unfortunately I can't get the answer easily and will need a weekend or two to pull both out and check.
When you say res-edit hack, do you mean to the system?
Whatever it is, the logic board is telling the analogue board directly to produce 640x480 (I don't think the Mac TV will do 512x384, but can't remember), so it could be coming from ROM, in which case, I suppose a hack would do it, but something tells me this is not the case.