You can use Thomas Bruckner's 3D Exploration plugin (from his website) to get 3D Exploration to open .iff files, which lets you convert it to any of the bazillion formats 3D Exploration supports. The mapping info should in theory remain untouched during the whole process, so you can just paint over Standoff's textures at will. I don't think there are any other methods that are as simple or as reliable as this.
For anyone else interested in this kind of thing, and for future reference, or what not... You are free to use Standoff's models provided you:
A) Come up with your own textures for them and
B) Don't ever release *anything* (as in, not even a 320x160 screenshot) that shows Standoff's models with any piece of the original texturing still showing.
The reason for this is not that I think my textures are particularly hot (they aren't), but rather:
1) I do not want other mods to look exactly like my own
2) I do not want other mods to look partially like my own, with the occasional completely different and absolutely out of place texture thrown in
3) I do not want any screenshots of unrelated projects being mistaken for Standoff ("I downloaded this game after seeing the Super Concordia Mk II screenshot on a random website, but now I played through the whole thing and I didn't find it in game! Standoff sucks!")