I have updated the MSDN Wiki with all IID's involved.
Another VERY important thing is that you don't have to add anything to the DOCPARSE.XML file. You have to register the parser using the OM.
SPFarm farm = SPFarm.Local;
SPWebService service = farm.Services.GetValue
SPDocumentParser customParser = new SPDocumentParser(CUSTOMPARSER_PROGID, extension);
service.PluggableParsers.Add(extension, customParser);
service.Update();
/Jonas