To replace some of the images (TuxMuch and the small image in the top righthand corner, IIRC) on 1.x players there is the setvisual package.
I have no idea if it works on 2.x versions though. But it might, as it searches for the images... If it messes up your player, just reinstall the .upgrade file.

It's not as easy as using the Logo Editor - you need to get to the shell prompt on the player, rz up a couple of files to the player and run a command line tool to actually replace the image(s)

Here's the original thread.

/Michael