For those wishing to use the VED to reduce curvature, it would be sensible to use a tried and tested system. The Peyronies Protocol (aka Multi-Cylinder Vacuum Protocol) is a multiple vacuum cylinder approach designed by Chris Spivey, of Urology Centers of Alabama, to treat peyronie's disease. You can see the reasoning behind its use here: VED Therapy.
I want to state that it's important not to have unrealistic expectations. This type of therapy will not work for all men, and some of those it does work for will have to stick at it for many months in order to see results. Do not over pump, else you will do more harm than good. Pressure does not need to be excessive, and there is no benefit from doing so.
The multi cylinder VED approach is used to stretch the peyronies scar is different ways. The small cylinder is more adept at stretching length, the large at girth, and so on. The protocol itself is 26 weeks long, but should you reach the end, there is no harm returning to week one and going through the whole process again.
Spivey on the site peyroniesprotocol.com recommends that each daily session should consist of ten cycles of these four steps:
a) Create negative pressure around the penis
b) Fill the space inside the cylinder and hold a "straight" erection for 5-10 seconds
c) Release the negative pressure in the cylinder
d) Repeat the cycle ten times to complete one daily session
If pain occurs you should of course stop the session and rest. Done correctly and without excessive pressure this is a good approach. Vacuum Therapy and Traction Therapy are the two mechanical methods of treating peyronie's disease. While they're unlikely to cure the condition as such, they can reduce curvature and improve sexual functioning. Aims which should be the primary concern of all peyronie's patients.