Fixed. You can now start playing, or start the demo going, but it fails with an SDL parachute (in the demo) when you go to pick up the grenade launcher (?).
Not sure if this is an SDL problem or a Quake one, any more info straces, other ways of getting it to fail, etc. appreciated.
Updated ipk in the link above & also just been added to OE.
Thanks,
Simon
P.S. there's also an unstripped quake binary in the directory I gave above which should be of use in tracking down the problem.