Some issues so far ...
If you install on drive other than C: ... you may have problems
I did ... I eventually ran the Q2LMDemo.exe into the 'base' folder.
But, I dont know if thats correct. But, it's running now.
There's no crosshair either.
The Original Doom3 desktop icon wont play Doom anymore.
Instead it opens the mod. But, that might be a configuration file that needs fixing ... I dunno