A .pcf file is really a .zip file containing (a) some .zip comments that mark it as pcf, (b) a ConfigEdit.xml file, and (c) a directory chock full o' bitmaps.

You'd need to unzip the information, edit ConfigEdit.xml, re-zip the information, and be sure that the .zip comments are correct. As I said, search around in this forum for instructions (Daniel's PCF uses hand-tweaked XML to change the Pronto icons, for example.)

Some of the .zip utilities will let you open the .zip, extract only the .xml file, edit, and re-zip just the .xml file into the .zip, without needing to manually deal with the comments.