Force automount of SD ONLY???

[acslam]

I tried on incredible forum and got someone asking if I've tried the obvious, so I'll try my luck here.

I've got an incredible, and was running the stock 2.1, rooted, and I had the phone set to automount the storage as a disk drive whenever connected to USB. Due to a bug in 2.1, whenever you set it up to mount automatically like this, ONLY the SD card was seen as a drive, and the phone storage portion was not available. You could make them both available, but not automatically.

This was PERFECT for me, because I have a car stereo that accepts USB disk drives, and all my music was on the SD card. The one limitation of the stereo is that it only reads the first available partition. Nothing I can do to change it. So, with that setup, it mounted only the SD, the stereo saw only the SD, and I was in music heaven.

So I got virtuous 3.01 loaded on there, and I love froyo.....except....they fixed the mounting bug, and now the phone properly presents BOTH the SD card and "phone storage" when it's plugged into USB. And of course, phone storage is the first presented partition. End result is my car stereo now CANNOT see ANY music stored on the phone. Worse yet, since it takes the phone some time to do this, the stereo doesn't always recognize that a usb drive is even plugged in, where the timing was absolutely perfect before and it picked it up every time.

This seems like it should be extremely simple, like there should be some setting in the phone to mount only one single partition when plugged into a usb port. But for some reason, after days of searching, I can't find this anywhere - everyone always has the opposite problem and wants to make it mount everything.

Can someone please point me in the direction of a setting (most preferable - since I know it worked under 2.1, I know the phone must be capable of this at the OS layer), an app, or SOMETHING, that just straight up automounts ONLY the SD card when plugged into USB?

Under 2.1, with the "bug", it worked FLAWLESSLY. Every time I got into the car, plugged it in, and bang, music. I don't wanna give up froyo because of this, but it's pretty frustrating. I hope maybe someone can show me what I've missed!