#mm

The search key for Emeril's l4d2 server is "superlucky"

I stole the rest of this from nova's post and updated it:

Go to \steamapps\common\left 4 dead 2\left4dead2\cfg\ and make a file called autoexec.cfg with the line "sv_search_key superlucky"

This ensures that when you create a lobby for friends the game will automatically join our server (where people will have rcon, etc) using the lobby settings (public, friends only, coop, versus, whatever.)

You only have to do this if you intend on being the host of a lobby. Otherwise you can be invited or join a game with friends as normal.