John,
He goes by the name of Phoenix on the Yahoo-based mailing list and his server is often linked to as hosting various XM-related stuff so he's not an outsider by any means. I don't know if he members here or not.
If I remember correctly, the chips in question communicate via the I2C protocol (very probable, after all, what else?). I also have a programmer for this but I built it and use it to reset my laser printer toner cartridges, not Citroën radios.
Actually, I didn't actually build it, I would have done it twenty years ago but these days, it was much simpler to buy it over the net from a specialist web store for a couple of euros... That way you have the software and everything included and it's USB rather than old serial or parallel which makes it much easier to handle now and in the future.
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