If you've already Enable Developer Console Commands then you're probably used to entering them in every time since they clear when you close down the game. You don't have to anymore. Here is how to automate it.
- Open notepad and drop in any commands (each on its own line) that you want to run when the game starts.
- Save the file (with quotes) as "autoexec.cfg". This preserves the extension if you have them set to be hidden within Windows.
- Create or drop your your autoexec.cfg file in: C:\Program Files\Steam\SteamApps\common\alien swarm\swarm\cfg
- You can also add these commands to newmapsettings.cfg as an alternative. It's inside the same folder you'll be putting autoexec.cfg in but probably best to leave that one alone.