Scorched 3D only supports ase and MS3D ASCII File formats. What I do is port them as .obj (when i model in sketchup) and import them into Milkshape.. then I export them to MS3D ASCII file format for the engine.
Scorched does support alpha textures, but only with bmp alphas (black is invisible, white is visible) overlayed on a texture.
Armorwraith here is link to zip of my LCC building in the format you said to use I zipped it up and uploaded it for you to look at, if it loads ok for you I can post the Air force base mesh and silo building meshes for you! MinutemanLaunchControlBuilding
The launch center looks great, but the textures will not be read properly by the engine.
-Scorched only supports alpha bmp atm, using two bmps, one colored and one to show where trasparency is on the original bmp.
I noticed some joints and bones in there? Was it animated? I get a wierd animation when I try to play it, but thats not really important. Easily fixable. I sent gavin a message letting him know you had some interest in contributing. He may take a while to reply, very busy man.
if we work out the kinks, and get you to know the engine youll prolly have a very good shot at making whatever you desire.
if you wished for the minuteman missile to break into seperate pieces during flight, you would need to model the missile as a whole, and to have it break you would need to model the after stages. (basically delete the bottom part export, then the middle export, then the top. export I would only model one warhead though, you can mirv those with the engine.)