Help with Left 4 Dead playing online

A friend and I both have L4D installed on our PCs because he bought it, and we share the account.
Is there a way that we could both play online together using the current installations we already have? Thanks for the help!!!
Answer #1
Seems unlikely – I assume you mean he bought it on DVD yes? If you mean the steam version then it’s a definite know, but I wouldn’t hold your breath for the Retail version either…
Answer #2
you can play split screen…
http://forums.steampowered.com/forums/showthread.php?t=745113
Answer #3
you can play split screen...
http://forums.steampowered.com/forums/showthread.php?t=745113
This is the best idea