The gist of it is that you eat normally up until 24 hours pre-race, at which point you do a workout of 2:30 at one mile race pace, followed immediately by a 30 second sprint, followed within a few minutes by embarking on the consumption of a large amount of carbs over the course of the day. Some details contained here and elsewhere:
http://www.pponline.co.uk/encyc/0974.htm
Doing that workout the day before a marathon seems risky, but does anyone have any actual experience with this? I think the studies were measuring glycogen storage, but not necessarily actual race performance, which is probably of more interest here.