I can only use leg drive on a single punch.

As soon as I start doing combination punches I cant dip 1 knee, raise the knee up again and dip the other knee in time, because my hips are rotating back n forth too quickly to allow for that slower movement.

The best I can do is bend both knees all the time and get some kind of half arsed leg drive for all the punches!

Hows it done? Or is it impossible?

No one on boxing scene knows lets see if the pros here will know