In practice, I keep two folders (one for ICE and one for TIC) and change the names of them depending upon which mod I want to play. I have a shortcut on my desk top so that I can quickly find the expansion folders and change the names manually. There may be a more sophisticated way of managing the ICE and TIC mods but this works for me.
Switching to
Total:IC mod: rename "ice" to "ice-OLD" (ICE folder);[/color] rename "ice-NEW" to "ice" (Total:IC folder).
Switching to
ICE mod: rename "ice" to "ice-NEW" (Total:IC folder); rename "ice-OLD" to "ice" (ICE folder).