You need to host the game as an xbox server then join it on PC works fine. dont ask me how to do that since i'm currently working on it
Ok well I see we are trying some of the same things so I'll share some information I found:
You can set the platform to "xenon", "ps3" or "win32" in the .cfg
(Xenon being the processor in an xbox.)
then also in the console you can type Game.Platform xenon, ps3, or win32
You can start a server instance as xbox or ps3 and auth just fine, but if you swap platforms after auth nothing happens as far as I can tell, I can't even manually enter the GUID on the battlelog to find it. If ya guys find anything let me know!
This should help you out list of consol commands you can do, I did alot of GSC coding back in the days of MW2 and this seems to be similar kinda c# stuff. I found someone from Freecam(the people who posted the beta files in the first place) posted all the commands Here they are