Set up your play book. There is a wish bone formation that uses a FB and your #1 and #2 HB's. Also if you're playing with PS2, you can do substitutions for each formation by tapping the O button. While selecting the formation, tap the O button and just below it will say something like HB sub, QB Sub, HB Slot whatever. If you select a play where you are replacing a receiver with a HB, your #2 HB will substitute in while your #1 HB will be playing the reciever spot.
If you want a solid running game, you should have the wishbone formation. Try it, you'll be a much better player because of it.