Try this:
alias FPS "firstperson; asw_hide_marine 1; asw_controls 0"
bind "v""fps"
Then use v to go first-person. I’ll let you all figure out the reversal to third person.
Some other cool stuff: the tile generator and it’s interactions with Hammer. See the Valve developer wiki (here) Seriously cool stuff. Procedural level generation? Yes please!
You can also enable the Director, although it has a tendency to kill you horribly by default (see http://www.rockpapershotgun.com/2010/07/20/verdict-alien-swarm/#comments).
I’ve actually got an idea that I’ve been toying with that Alien Swarm’s tools make a helluva lot easier. Will fill in anyone who is interested…