That sounds really interesting, and something that could easily be done. Rockbox is freely redistributable, but with certain conditions you must comply with.  For full details of Rockbox's license, see: http://svn.rockbox.org/viewvc.cgi/trunk/docs/COPYING

Rockbox has a contact-address for press-inquires, so I suggest you contact press_AT_rockbox.org instead of me, as I am just one contributor among hundreds. I'm sure they'll be helpful and willing to answer any questions you might have.