IO540, as with most things with this stuff, the trouble with airways is the data. If someone gives me the lat/lon of all the airways then it'd be no big deal to add that function. Until then, just enter the VORs that define the airways (which will be okay but for the kinks in them). Actually I guess an intersection database would probably get us most of the way there.
I see somebody has already answered this so I will just add that it "should" be easy to get all this data, worldwide, because somebody has done an airways overlay for the NASA World World Wind software. It must be there somewhere. I would start with DAFIF but that database will be closed to the public (courtesy of Osama BL) this autumn. After that, EAD Eurocontrol is the next place to look.