add app to empty boxes in froyo car home

If you swipe right in the froyo car home, there are two more app shortcuts: maps and settings. There are also four empty boxes. It seems intuitive that a long press would allow you to add an app to these empty boxes right? Well it doesn't. There is no menu to do so and I don't know where the car home settings are otherwise. I'd like to fill some of these boxes, with apps like pandora or trapster, and actually wouldn't mind sorting the apps that are already there. Is this possible? Can someone help me out?