perhaps this is what you seek, look at post #8
http://pdaphonehome.com/forums/ppc-6...ng-thread.html
i changed mine to vibrate for 2 seconds and wait 1 second in between instead of the default 3 second vibrate wait 3 seconds in between.
Only problem with this, when you change any other sound notification the "regular" way using settings, this gets resetted. As a matter of fact, for me if you go to Settings, then sounds and notification, no matter what you change, it will go from vibrate to ring.