Yes. That is, if the program is NOT in the ROM you can. The easiest way is find the program on your PPC. Copy all the .dll and .exe files onto your PC.
Download
Resource Hacker (freeware). Open the .dll or .exe files and find the bitmap icons.
Then you can export the bitmap and edit using MSPaint. After editing, import them back using Resource Hacker and save the file. Copying it back over to your PPC and it should work.