Update 2011/02/24:
You can now create Blitz dedicated servers both with the standalone game and dedicated server installations.
You can install a dedicated server for Windows using Steam's HLDSUpdateTool. Sadly, there is no Linux dedicated server.
The command to install it using HLDSUpdateTool is:
HldsUpdateTool.exe -command update -game mondaynightcombat -dir INSTALLDIR
where INSTALLDIR is the directory you want to install the server to.
The dedicated server command line to run a Blitz server is:
mnc.exe server HostileLobby?game=HostileGame.HGameInfo_PreGameLobby?GameType=TeamBlitz?ServerDescription="My Blitz Server"?MapName=3?CoopChallenge=3
Replace "My Blitz Server" with you server name.
Valid range for MapName and CoopChallenge is [0,5]. These values must be the same for servers to correctly display in the server browser!
0 = Exhibition
1 = Season
2 = Playoff
3 = Scramble
4 = Sudden Death
5 = Super Sudden Death