I'm posting this in the mods forum because most of the unit makers come here I think.

To get the 3DO texture mapping working, you have to select texture archives through the menu. Only zip/sdz archives are supported right now. Because upspring doesn't have access to the GAF files, you have to create texture groups yourself. These texture groups are saved in texgroups.cfg. Just play around with the texture group dialog and you'll see...
About the S3O texture mapping, you need to make sure the texture names are without path (This is fixed now, the previous version didn't actually save what was in the text box). I also found that S3O textures need to be put in the unittextures map, instead of unittextures/tatex so I'm hoping this fixes a lot of S3O problems.
Another thing, a bug: the 3D view with lighting doesn't display the selection. It has been a while ago since I used OpenGL so I'm probably doing something wrong with the colors...
And if anyone has time to make me a few nice looking button images, I'd appreciate it.
edit: Two extra notes:
-There is support for the Wavefront OBJ file format, this only saves single pieces though, no trees.
-The example team color is not used, S3O texturing currently uses the RGB from the first texture and not more.