Thanks to a lot of people on the Raspberry Pi forums, I was able to get Quake 3 up and running with a fairly small amount of effort. As I don't own the game itself I'm simply playing the demo levels, but that's more than enough for now, as I've realised I'm particularly bad it would seem. I wasn't ever much of a gamer, but was addicted to Quake 1 & spent a fair amount of time on Quake 3, but it would appear the years have robbed me of the meagre skills that I spent days and weeks of my youth building up.
But, regardless of the number of times I've had to start a new game, it's still bloody cool. Playing it at 1080p on my 40" LCD looks beautiful!
As with the other tutorials I've created separated pages for them - hopefully this should give you everything you need to get Quake 3 up and running. As always, let me know how you get on, and if you hit anything I haven't covered.