Configure the Vibrato Lever

[Penguin666]

Hello there!

I got a Jupiter 50 but I'm taking my chance here, as I guess it's the same configuration:

I'm looking for a way to configure the Vibrato when I use the lever on the left of the keyboard. I'd like to adjust the rate or the depth of the vibrato but I can't see how to make it.
I found in the manual how to adjust the pitch bend with the lever, but nothing about the vibrato (using the lever).
Anyone does know if it's possibe?
Thanks!
Phlppe