Outdated: Haven't really gotten to test it so I expect I made an error somewhere, possible in signing the app or whatnot. I'll fix it tomorrow.
P.S. For anyone who doesn't know what Rockbox is: http://www.rockbox.org/wiki/WhyRockbox
Edit: Noticed some issues then realized I compiled it for 640 x 480 landscape not 480 x 640 portrait like it should be. Uploaded a new version. *Crosses fingers*
Edit 2: To fix the tiny font follow these steps:
1. Download and extract this and extract it to your sdcard so you have a folder called "fonts" at the root of your sdcard.
2. Open terminal emulator and type: su
3. Type cd sdcard
4. Type cp -af fonts /data/data/org.rockbox/app_rockbox/rockbox
That should do it. It should now look like the second screenshot when you open rockbox. I'll see if I can incorporate the fonts into the apk but not sure how to do that right now.
Edit 3: Wow, just discovered something. You can just copy the fonts folder the the "rockbox" folder at the root of your sdcard. Makes it significantly easier.