Im not sure how it can be manipulated to work with a gym, but I have two brothers who have been doing just the regular P90 and one of them has lost over 90 lbs!!!
Yes the program actually works. AND IT WORKS WELL! as for the gym, ive seen people have ipod touches and stuff with the videos going that they are doing the program. As for the exercises, they are great. the program was made to be a whole program, but that doesn't mean that the exercises are bad by themselves.