PPCGeeks - Make external ringer work while headphones plugged in

Is this possible? I use a headset/mic for my phone while I am in the car driving. The problem is that I hate to keep the headset on my head unless I am on a call, but prefer to keep it plugged in for convenience.

I keep the phone beside me on the seat. When the phone rings, it only rings through the heads set, and I miss the call (unless I see the d-ring light up).

Is there any way (reg tweak), or software that will allow me to use the headset plugged in, and still have the ringer ring on the external speaker?
I used to own a treo (palm) and I had the ability to do this?

I also posted this ? at our friends at XDA.