I skid on about the same number of gear inches just fine. You don't need to change it.
I'm guessing that you're thinking of skidding more as something like: Pedals go around, and then at one moment you push/pull with you legs with all your might and skid.
It's more about timing and properly getting your weight over the back pedal. Try riding around and letting the pedals push your back leg, and you, off your saddle. You sort of need to become dead weight on the bike, and just let the momentum push you off the saddle. So, with that feel, once your back leg (or what will be your back leg once you start the skid) approaches 6-o'clock, stiffen and extend it, and let the pedal start to push your body upwards. Around the same time, you should pull up with your front leg. Once you get to around 3 and 9-o'clock, you'll get to a point where you can almost feel the drive train wanting to lock-up. It's ok to try it at slow speeds first to get a feel for it.