The week long "train-up" is actually 3-6 weeks of training and/or experience.
There are four main components: "Prep" for the field, Bushmaster& Kerkesner (done in conjunction at FIG, total of ~ 2 weeks), and military medical field training.
1) "Prep": We spent about a week sitting in classes, and learning some fieldcraft (how to put together a ruck-sack, read a compass, move a fire-team, etc). Not a bad experience, but most people in my class thought the material could have been covered much more quickly, and didn't get a whole lot out of it.
2) Kerkesner: ~a week of decent field training at Fort Indiantown Gap, PA. You live in tents (sleeping on very cushy civilian cots), no AC, no showers...the stuff we army folk signed up for. The training was actually pretty good: Mass casualty excercises, 9mm familiarization, Battalion Aid Station ops/jumping (moveing from one spot to another), land nav, paintball care under fire, rapelling...overall a pretty good time. If you've never spent any time in the field, the worst part of it is the Penn. heat, and learning to stay clean without showers. The best part...it's a lot of fun if you're not the whiny b*tch type, and the training is pretty good.
3) Bushmaster: Between MSIII and MSIV, all USUHS student participate in a large scale military medical excercise for ~10 days. They are airlifted to Fort Indiantown Gap (we bus up), and deploy into battalion aid stations, combat support hospital, etc and are evaluated on operations, pt care, and all 'round hooya-ness. The asset that is most difficult to find is good patients...that's where the MSI/IIs (not sure what we were at that point); we were the patients. Kinda fun actually. We got dressed in full moulage, and acted like whatever we had was real from open skull fractures to STDs, to broken legs, to colds. More importantly, it was a very good look into what we'll be expected to do in a couple years. Learned a lot about the operations of various assets, and more importantly got to see all the "stupid" things that the MSIVs were doing. We all say we'll remember the "stupid" things they did, and never repeat thier mistakes, but we all know it's inevitable. The up-side, you live in barracks during this operation, the downside can get kinda boring waiting to be a patient.
4) MMFT: If you have no experience in the military (which does not include ROTC or the academies) then you get to go spend a couple weeks with an army unit to experience what real soldiers do. This is supposed to be non-medical in nature, several of my class mates went to aviation units and rode in helos, some went to SF groups, some went to the 82nd, some to San Diego, a couple to Germany, and some to South America. Overall, most people were satisfied with the experience. I'm not sure that 2 weeks gives a person a real idea of how the military works, but it's better than nothing.
The people with prior experience were encouraged to participate in research locally, or find some other military activity that doesn't cost the school money...we were completely unfunded.
Oh yeah...we took leave before this whole process started, and class started right after mmft.
I'm sure I was incomplete and/or included minor innaccuracies, so take it easy on me. I should be studying neuropath right now.
I hope this helps.