Andrew, without knowing how much time you have to train before the trek, I cannot provide an answer to that portion of the question.
Time between trek and ride is 4 days...much of this has to be based on how stiff, sore or banged up you feel, but this is an idea of what I would do.
Day 1 - Lots of rest, hot bath, and massage. Ride bike on lightest gear for 20-45 minutes.
Lightly stretch - focus on core and lower body. Eat only natural, organic, healthy foods
and lots of liquids.
Day 2 - Same as above but increase spin time to 30-60 minutes.
Day 3 - Same as above, but do an hour on the bike and if your body can handle it, stand out of the saddle and use the gears to add resistance, nothing crazy, but you want to push some blood into your muscles...if you are still way too sore - just spin lightly as described above, but increase spin time to 60-75 minutes.
Day 4 - If you were not able to add resistance on Day 3 do so now. If you were able to do resistance on Day 3, then spin 60-90 minutes extremely light.
My experience is an active yet gentle recovery works best. Your legs are going to want to stiffen up, so the main goal is to keep them warm and loose! If no one will give you a massage, I suggest buying a massager. This is the one I use and it is awesome!