Best way to improve my vertical quickly

[vikefan24]

I'm 20, and would like to be able to dunk at least once before I die.. I can't quite hang on the rim but an inch would do the trick.. I think 6-7" would be enough to dunk(maybe I'm off)
I use one of these at the gym:


and was wondering if I am supposed to use light weight and explode or heavy and go slow.. I also squat, and should probably start jumping rope..

any other tips