This is a free desktop companion program to the myKbd hex keyboard utility for the Palm T3, T5, LifeDrive and TX. This companion lets you change the colors and layout of hex keyboards. You edit a keyboard by editing a fairly simple text file that describes the colors and layouts (see SampleKeyboard.txt which includes instructions) and running GO.exe to generate the keyboard skin which you can then hotsync. Please read readme.txt before using. You may need to download a free Java Runtime Environment to use. This is for Windows but includes source code (except for the java batik code which should be platform-independent) so it shouldn't be that hard to get working on Linux or OS X if you know what you're doing.
Updated Description:

1.20: Added RELABEL and REFORMAT sections to control text and formatting of individual keys or key ranges. Added font style and font weight controls. Added FONT-WEIGHT and FONT-STYLE commands to allow bold and italic labels. See SampleKeyboard.txt for more information.