The tip is: do not use the brakes fully.
When you're in high speeds you can even do it, but while the speed is decreasing and you are leaning you must release the brakes smoothly.
I did this because if you brake too strong, while you lean, you get a lowside crash... I don't know exactly how are the brakes of MotoGP, but if is hydraulic(like mostly of the bikes in the world) you never uses the brake fully... I mean, if you want to do this you need to use your four fingers and much strength, and these pilots use only two (Stoner just one)... But the joypad don't have this hydraulic resistance... So you need to be balanced when using the brakes
Try in a Yamaha or Suzuki, these two are more stable in braking and cornering. The Ducati is the worst...
But is really hard to balance this force with the joypad trigger... When you get used to it, at least for me, it's more "rewarding" you hit the braking point, or try to force a little more the braking point...