The Google found a few possible sources:
https://www.download-geek.com/downlo...aff.subid=7005
http://www.coolsky.no/public_downloa...r%20Manual.pdf
http://aviationarchives.********.com...operating.html
The first one requires some kind of "free" sign-up which I refuse to do so I don't know if the material is any good. The 3rd one looks like it has potential.
DC9 systems are pretty simple as these things go.
If you've spent money with a TRO, will they send you the manual ahead of time so you can study before school ?
P.S. OK....that 3rd link won't work as posted here but Google around and you'll get it to work.