Well I went ahead and installed A2 onto the machine where OA was already installed.
The _runA2CO_nonSteamOA works, however when I run the A2 Benchmark 1 from CO it crashes the game (freeze needing force quit). The A2 Benchmark 1 runs fine if launched after a non CO A2 launch. I tested an A2 mission and it worked from the CO launch but just an FYI that the Benchmark FREEZES the application during load.
Also my registry entires ARE NOT what is illustarted in the sticky. I am running Win 7 64.
Additionally just an FYI, I used the default directory paths during install and this is where they went. Not sure if it is an issue:
C:\Program Files (x86)\Bohemia Interactive\ArmA 2 Operation Arrowhead
C:\Program files\Bohemia Interactive\ArmA 2