RD300GX - (possibly stupid) MIDI Question

[TVPG]

Something of a shot in the dark here, I'm wondering if it's in any way possible to use the RD as a USB-MIDI interface, possibly by somehow setting the USB MIDI input on the board to "MIDI Thru," so MIDI messages are just passed through to the MIDI Out port.
I'm fairly new to MIDI (if it wasn't obvious) and it seems that MIDI Thru functionality would be handy for other purposes as well.
All I'm looking to do right now is send SysEx messages to another device from my computer, and I don't have a USB-MIDI interface device handy; thought maybe this would work but at this point it really doesn't look like it.
Any help, explanations, or ridicule would be appreciated.

Thanks!