I've wrote a little script to install Chocolate Doom onto your Pi as well as Doom1.WAD. This is my first script and constructive criticism is greatly appreciated. This will only work on Raspbian.
Either download directly from here, and ssh onto your device: http://www.mediafire.com/?3onopxcrtdba1lr
Or use this command: wget http://188.8.131.52/xixu48a6avdg/3ono ... ateInstall
Then type "sudo ./ChocolateInstall" in the directory you downloaded it to.