Here is what I found at the all deaf site:
Originally Posted by RickL66
You can get Message Alerts, it lets you set the vibration up to 10 times and you can set the vibration duration too. Example, if you set the vibration to 5 and duration to 4, that means it will vibrate a total 20 seconds (brrrrrrrrrrrrrrr 4 seconds [pause] brrrrrrrrrrrrrrr 4 seconds [pause] brrrrrrrrrrrrrr 4 seconds [pause] brrrrrrrrrrr 4 seconds [pause] brrrrrrrrrrr 4 seconds and done).
It is very nice, I can set it to custom alert me, for example, if I get a message from my wife, I set it to 5 vibrates and 1 sec duration (fast "beeps") vs others will be 4 vibrations and 3 second duration, so I can easily tell if the incoming message is from my wife or not. "+mablackberry+"
<-- click here. It cost $24.95
Exactly what I'm looking for... but a bit pricey at $25 :(