Well, the majority of people who went on mine were from colleges on the Uniformed Services course. But there were a few exceptions. A couple of lads had their PRMC in a few weeks and their AFCO put them on the course.
So you would probably need to contact your AFCO about it. I'm not sure what the requirements are to get on a trip without being at college. Maybe if the course has a few spaces left individuals can apply to fill them up.
On the one i went on we went through the Endurance Course and the Assault Course. We did the 3 miler. We did the swimming assessment and a bit of messing about in the pool. We did some indoor rock climbing, unarmed combat a bit of phys and log PT on bottomfield. On the last day we went to Woodbury Common and did a bit of field craft, putting tents up, cooking rations and putting camo on etc. And we also did some 'stalking' were you camouflage up and one team has to try and crawl through this thick grassy field up to the other team without being spotted. Ummm.. we went on the virtual rifle range, had a few lecture about Marine life, spoke to some Marines in training, saw the mueseem and thats pretty much all i can remember.
It was a real fun time and a great insight too. You can see some photos of my trip
HERE.
Oh and the course lasted 5 days. Although we didn't do much on the first and last day.