The Shock Treatment soundtrack's orchestration consists of:
- Drum Kit
- Bass Guitar
- 2 Guitars (Electric & Acoustic playing Rhythmn & Lead)
- 2 Keyboards (Piano/Synth)
- 7 Piece Brass Section (2 Trumpets/3 Saxophones/2 Trombones)
Any professional rock musician you would hire should be able to play along with the lead sheet chord symbols found on the 2 websites listed (they appear to be in the correct keys.) So playing directly from these chord sheets is possible. But...
Big issue #1 is the horn arrangement. On the soundtrack, they sound like they play mostly in unison with very minimal harmonies. One of your hired horn players may be apt to do the horn arrangement for you. You also may consider dropping the horns and play the part on Synth keyboads, or only have 1 Saxophone just like Rocky Horror.
Big issue #2 is the vocal/chorus score. Your lead singers should be able to follow along, but there's distinct choral harmonies in the larger ensemble songs ("Denton USA" and "Thank God I'm A Man".) You can again simplfy with very basic harmony that your piano player can figure out. Or consider having the chorus sing in unison.
Big issue #3 is you'll need to figure out how you are going to perform the material. I've only been taking about Shock Treatment. RHPS, The Stripper, Return of Captain Invincible and any other R.O'B songs you may consider each have very different instrumentions, so you'll want to come up with a consistant ensemble of players and instruments to perform the various numbers.
As an East Coast theatre musician and arranger, I can tell you first hand that it will take WEEKS, if not MONTHS to fully transcribe melodies, harmonies and orchestrate for this score. It's not a job you can ask anybody lightly. Your best bet is to find a few local rock musicans (sans horns) from craigslist, give them each a CD of songs, print out the lead sheets and have at it.