Good news. I've figured out the kinks with it.
To add a custom loading screen to a custom module, you do as I said before. Just name the tga file "load_MODULENAME".
Before it worked for me on some modules, but not others. After a bit of experimenting here and there, I've figured it out. There seems to be some character limit or something in the filenames of the loading screens.
For example the loading screen for the module "bos_mandship2", which was named "load_bos_mandship2" didn't work. Yet when I renamed the mod file to "bos_msp2", and then the load screen to "load_bos_msp2" - Everything worked fine. :)
Anyways, for those interested, this is the loading screen I created. I'm pretty happy with it.
http://img.photobucket.com/albums/v642/Silveredge9/load_BOS.jpg)