This is from pre-3.02 since any attack with your pet on defensive makes your pet attack also. I use 2 keys for attack and follow for pets (hunter and warlock). I use F1 and F2 since they are easy to get to and mash in a microsecond. F1 is just /petattack and F2 is just /petfollow. It allows me to pull my pets back in combat (don't attack that, pull mob back to me, etc).

With 3.02, you might have to put in a /petpassive just incase you had the pet in defensive. The trick is the pet will do the last thing you told it to do. So you have to put follow last or it will attack if petattack is last.

/petattack [harm]

/petpassive [mod:shift]

The trick is /petpassive should (should) make your pet follow no matter what it was doing before. So you probably don't need a /petfollow at all. Don't forget you automatically get keys for pet actions. (CTRL-1 for far left action---petattack, CTRL-0 for far right---petpassive)

Hope that helps.