Could, in theory, the supercharger from the 2.0L S/C Ecotec (Cobalt SC/SS, Ion Redline, et. al.), or any of the aftermarket stage 2 or stage 3's meant ofr the S/C 2.0L fit on the N/A 2.2 or 2.4 Ecotecs with very little or no modification to the mount points or TB? I would assume that all the Ecotec engines are the same on the outside, and that a retrofit installation would be somewhat direct. Are there differences in the throttle bodies and mount points that would prevent this?

The 2.0 is a dedicated forced-induction block, originally designed for turbocharging. There are a number of differences so it's certainly possible the induction systems may not be transferable.

GM does have a supercharger for the 2.2L Ecotec, but it's for the Cavalier/Sunfire, and will not fit without some custom fabrication. I believe they are going forward with a S/C for the 2.2L Cobalts.

prolly some slight differences in the intake, for higher flow in the bigger ones, not to mention less comp. in the 2.0