This didn't work for me running the original SMAC, but it did for Alien Crossfire. In SMAC the resolution change worked, but the controls were all screwed up. The menus on the start screen were invisible, although still clearly there (they reacted to mouse clicks, if I could figure out where the mouse was without visual feedback) and the information bar during gameplay showed up in the middle of the screen, not at the bottom. Everything worked great in Alien Crossfire.
I realize this is really an old thread. And it's not a big deal since it works with the Alien Crossfire extension, but I thought this was worth posting in case someone searches for "Screen Resolution change" sees this and tries to run this resolution fix in SMAC and not Alien Crossfire.