I'm pretty sure it's not possible, the H10 wasn't designed for OTG, and anyway it would require modifying the USB cable (since the H10 has a proprietary connector...)
Also, it would require working USB in Rockbox (currently USB transactions are done by the OF in UMS mode, and there's no way of getting OTG in the OF) which last I heard was working well enough if one wanted to play with it (by enabling USB in their own build), but is not yet commited to SVN since there's still some work to be done.