Since the six folks that I know tried using this in FS9 failed, but Eric Marciano succeeded (presumably by creating a C "helper gauge"), I conclude that it is not possible to use this "system" in FS9.

 

I haven't had the time to investigate, nor do I have any real interest in FS9 at this juncture, but I suspect that using the C equivalent probably does work, and it was only the changes in the XML parsing engine for FSX that allowed it to work via XML commands in FSX.

I tried, but failed a long time ago and now again.

Anyway, not so important, fly in friendly airspace....