Thanks, when trying to set up a build environment for FF on Mac OS X I nearly gave up a couple of times! Videos would have really helped, rather than a recursively complex set of wikis (Which was my recollection of what the docs were like - may be wrong/out of date.)
Given that the hackaton might be 2 days, unless your idea is 'simple' enough to have a MVP in 1 day (never seen it happen), the second day will be all preparation for the presentation because this is what will win a jury.