USB with Dual Modes- one at a time

Any suggestions on how to load up one USB config on power up based on a push buttons' position? Thought this might be easy, but seemingly not.

I have developed several USB devices that when operating, act as HID keyboard devices. I have been using the 18F4550. Simple, no problem. But I am now looking for an easy way to start my device in a configuration mode when a button is pressed during power up. In this mode I want the device to enumerate as a CDC /Serial device. In this mode I will be simply setting config parameters that will be stored as eeprom data, using Hyperterminal.

Not looking for a composite USB device really. Only one operates at a time. Any ides?

Thanks!

http://www.picbasic.co.uk/forum/showthread.php?t=4093