Automatically enable vibrate when silent?

[Xjph]

I've seen a few other questions about how to keep vibrate on when a phone is switched to "silent" mode, but that doesn't quite do what I'm looking for. I want to keep vibration disabled while the ringer is turned up, and to automatically enable vibrate when the ringer volume is set to vibrate, as opposed to just disabling the ringer and leaving the vibrate setting wherever it was previously.

 

[chrlswltrs]

I use WidgetLocker for my lockscreen. One of its many options is that when you slide to silence you can have it go into vibrate mode instead, that is what I do and it works great.