If this was to be done so easily, we would have done it a long time ago already. The only module that plays Calamus a trick to get coloured icons, is Paint.
Please imagine the function panel you see is not a building of several icons like buttons and stuff, but it's only an IMAGE which is handled in uncommented, ugly Assembler blackbox stuff from a Calamus developer who no longer is available, written in 1986.
Would you like to puzzle out how this panel engine really works? It's thousands of lines pure Assembler code. We rather look for a new panel engine.