Sorry for the unhelpful answer I happen to be compiling a kernel right now (for my laptop, not for the N900), so I spotted the CONFIG_USB_OTG (USB on-the-go) option. I imagine that's where the protocol takes place. Meaning that at least there one would be able to manipulate how the N900 presents itself to a USB host. I suffer severe lack of time but I'll add this to my list. I just have to find the damned list first Good luck!