seeing as the empeg can decode the 57 KHz subcarrier for the RDS service, why can't we tune it to the 67, 92, and in some cases 41 KHz subcarriers for the aux programing?

No clue. I've never seen anybody else ever ask for this feature.

The Temic tuner module is extracting the stream and the Phillips DSP is doing the RDS decoding. You'll have to read the documentation for both to see if you can do what you want. I think they're linked somewhere in the Riocar.org FAQ.

Ok I'll read the FAQ again

More likely that'll be in the developer info section if it even exists. I don't think it's in the FAQ.

I remember reading the interface spec when I first got the tunner years ago. If I'm not mistaken the FM disscrimanator output is fed to a DSP that decodes the stereo and RDS datafrom it's 57KHz carrier. My reasoning being that if it can do that it can decode the 67 or 92 KHz audio carriers.

EDIT What I've found so far.

FM stereo signals consist of

Left + Right audio
19 KHz pilot carrier
Left - Right audio on a 38 KHz SUBcarrier using Double-Sideband
Suppressed Carrier modulation (a type of AM)
optional RDS data on a 57 KHz SUBcarrier again using DSSC.
optional 67 KHz SUBcarrier using FM modulation.
optional 92 KHz SUBcarrier using FM modulation.
reference to an old 41 KHz subcarrier no longer used.

Interisting... looks like DAB may be coming to the US on normal 88 to 108MHz stations.

I read a report on how it affects SCA, RDS, and normal FM reception when the DAB signal is intergrated into the standard transmission.