Changing Ratings on the Cowon X9 (or any)?

[zenflesh]

I am fairly accustomed to using the ratings feature ("5 stars" on iPod touch, or heart/broken heart on Zune) as a way to quickly filter my music as I listen to it. Most of my interaction with my music library is via a mobile device. So, is there any way to change ratings directly on the Cowon X9? If not, is this possible on any Cowon players? Thanks!