How to accelerate with aut. gearboxes

[alfu]

Hello:

I want to know how can I have the maximum accel. possible with an aut. trans, because my car is a little slow at low RPMs (below 3000). I've an Opel Omega MV6 3.0 (Caddy Catera in the US).
Can I accel. and brake at the same time?
When I do that can I've a better accel.?
It's too bad for the trans. doing that?

Thanks