All the files are on fileuniverse, but it's non-obvious what to do to make it work.
Here's what you need:
First, you need the mod pack with the buildpics. The OTA + Evo mod contains the files needed for UTASP, as that's where its buildpics originated. Grab that and install it.
http://www.fileuniverse.com/?p=showitem&ID=1257
Second, you'll need the actual UTASP mod file, in .UFO format. Grab that off fileuniverse and plop it into your /mods directory.
http://www.fileuniverse.com/?p=showitem&ID=1047
Third, you'll need the Spring .sd7 format mod info file. This tells Spring how to use what's in the .ufo mod, and what other files the mod depends on. Grab it off fileuniverse, and plop it into your /mods directory as well.
http://www.fileuniverse.com/?p=showitem&ID=1431
Note: I made neither the UTASP5 mod, nor did I make the .sd7 modinfo file for the Spring switcher. I'm just putting down what I did to make it work.
Caveats: Some of the units have bugs, because they haven't been converted for Spring's slightly different way of doing things. For example, the Arm Orcone's primary weapon just drops at it's feet when firing - which is painful. I've got that one fixed in my personal copy of UTASP - it just needed startvelocity and weaponacceleration tags in the weapon description.
Anyone interested in converting this to Spring? Anyone else like UTASP?
*listens to the crickets chirp*