Well What your talking about is MPI (multiplayer instant action)
and thats not going to be added in to bz for 1.5 maybe 1.6 (or what ever the next update is...) but you could always sit in the Teamspeak server and play single player or one of the instant action missions while your friend comes on.
There are a few heavily modded Pre MPI maps but....There not very good and no one can figure out how to make the enemy build more units.
Oh and have you seen the new 1.5 AI?
You wont be laughing at the bz AI anymore its finally been fixed. (expect for the stupid scavs.....

)
And watch you never post here again
No but really you should post here again, we need some new blood.