You can hit a drive, but it doesn't have the power of a normal topspin groundie. Nor does it have to be, since you are supplied with incoming ball power. It's very effective when the server is used to your slice returns.
Turn shoulders with your OTHER hand, on the throat of your racket.
You need only 1/2 your normal takeback, because the incoming serve is faster than any groundstroke you will ever see.
If you have time, it's best to close your stance by moving the forwards. If you are facing 1st serves, you can stay on the balls of your feet and hit it open stanced.
Aim slightly higher over the net at first, as you will mishit some, and if you are hitting long, loosen your grip. Conversely, if you are hitting short, tighten your grip.
Never ever retreat.