If anyone is still interested this is where I am with a custom firmware for rk2606.
Basically I'm creating a music player for visually impaired like me!
The font is much bigger and clearer and the icons are too and the ID3 tags now scroll across if they are too big, it's starting to look much better thanks to the SDK.
I created a new bitmapped font(18x20) to completely replace the poor system (12x8) font.