Is there anyway to have your pet auto-assist you?

[redial2]

I was wondering if there is a way to have your pet auto-assist.

For example.
You target mob 'X'.
You begin attacking mob 'X'.
--
Instead of having to command your pet to attack, it just assists you on whatever mob you are currently attacking.

Is this possible, or am I stuck with having to order my pet to attack everytime?

-REDIAL2