I have the family friendly sirius package, and I just noticed that my channel lineup has channels that do not have a number, but instead have either sir-2, sir-1, sir-4. How can I tune those channels?

Can you use the channel up/ down buttons to access them on your unit? Then add them to your presets.

Sir stands for Sirius Internet Radio. These are internet only radio stations. I think that you need the Sirius Everything or higher package for internet radio.
SIR-1 is a feed of NPR.
SIR-2 is Viva.
SIR-3 is the Bob Edwards Show.
SIR-4 is Mad Dog Unleashed.