PSP HDD via remote port Ideas/ Questions/ Thoughts

I'm interested in programming a driver for the PSP, possibly using Nanodesktop, that will allow access to USB devices -- such as an external hard drive -- through the remote/ serial port. As other non-host USB devices, such as GPS have been proven to work through this port, this may be possible. PSP Remote Port- to-USB cables and adapters already exist, such as these PC-Mobile cables and these from Moby. My understanding is that the remote interface uses an RS-232 protocol, but voltage is limited to 2.5 volts. This would require that the external device be self-powered, or perhaps power could be introduced into the cable somehow, but it should at least allow two-way communication, if not host control.

I wonder if anyone has already started work on such a homebrew driver that will allow USB access through the remote port, and if not, is it because there are technical hurdles that make it impossible? I am new to programming on the PSP and would rather not go trudging down a dead-end alley. On the other hand, this would obviously be a major breakthrough for the PSP.