Piet,
If you are able to find Panasonic airconditioning codes on the Internet in Pronto HEX format, then I can convert them for you otherwise the only way to create a working XML file is to capture the codes from the remote.
Many airconditioning company's particularly ones with LCD status screens on the remotes don't just send the button pressed, they send the current settings of all buttons at the same time. If your air conditioning unit has a remote with an LCD screen, then it is not likely that anyone has it on their pronto because the Pronto does not have enough memory for such a long command, BUT the Beo5 does have enough.