I played a bit with rmmod and insmod for the usb devices. It seems that on the k5, host mode is always loaded, so that driver must be for the internal USB port:
http://www.aptasys.eu/weeco/?p=382
We may need a patched ehci-hcd.ko to work with the external USB port, as mentioned elsewhere by
ixtab.
EDIT: Obviously, I am connected to wifi SSH on my k5 (not USBnet), to test changing USB modes.