Play as infected in Left 4 Dead 2 demo? Here's how

The Left 4 Dead 2 demo is a great time, but the lack of versus mode play with the new infected is something of a disappointment. You won't have to wait until the game launches on the 15th, however; a clever chap out there has created a plug-in to allow you to play competitive games with the demo, and to try out the new special infected.

Here's what you do: