An xcf-file is nothing but a zip file, that contains an XML-file named ConfigEdit.xml, as well as a number of bitmaps in png format. You can, possibly after renaming open an xcf file with "any" achiever program, Winzip or 7zip, or ... then you can extract ConfigEdit, which contains all data, in a fairly easy to decode way. IrScrutinizer's xcf importer does exactly this.