HXFTool by so9 allows you to change the firmware files.

Features:

– integrated hex-viewer for single files inside the hxf-package
– change bootscreens
– change a few default settings
– language editor for english-texts
– some automatic patches (including the td-mod)

http://dl.openhandhelds.org/cgi-bin/dingoo.cgi?0,0,0,0,116,45