I did some of these techniques when I was a high jumper at IU.
Basically, I did plyometrics with weights. I'd do the box jumping with a weighted vest/back back, weighted jump ropes, standing jumps with weights... basically, I did regular training with weights and explosiveness. I got gains pretty fast, however... but remember, I was already in great jumping shape as it was... so it was just a matter of pushing myself further.
C-ditty