I\'m not sure if I understand what you are saying, so I\'ll just go through this step-by-step.
Lets say you choose 3 players, A=Ryu, B=Joe, C=Blanka.
When you get to the order select screen, you can decide which order you want your characters to be in.
If you want Blanka(C) to be first, Ryu(A) to be second, and Joe(

to be third, you would press this (assuming you kept the default controls):
fierce punch + fierce kick (R1 +R2) , then weak punch + weak kick (Square + X).
If you want the order to be C,B,A you would do this:
R1 + R2, then Triangle + Circle.
If you want the order to be A,C,B, you would do this:
Square + X, R1+R2.
I hope that helps.
EDIT: Ryu, if you want to have your guys come out completely opposite of the order you chose them, then you would need to press two button combinations. But other than that, your right about only needing to press 1 combination of buttons.