HI Ernia,
Sorry I meant icons-prescaled that gerritv provided means you don't have to do any conversion. they are ready to use.
icons-prescaled is a tar file. (but is missing a .tar extension) you need to run
tar -xvf icons-prescaled
(or if you haven't arleady gunzipped the file)
tar -zxvf icons-prescaled.gz
in order to extract all the icons inside your xpm folder.