Let me know what you hear.  I've seen the same problems...

FlexFax work3ed fine for me, HylaFax isn't...it receives faxes, but
it fails to launch the getty (actually the getty tries to run and 
pukes...).

It looks like HylaFax's faxgetty establishes the tty and itself as 
session leader (which seems kind of bone headed for it to do) and then getty 
bails when it can't do the same.  If I give faxgetty the no tty flag, then
getty gets EIO the first time it tries to read stdin.
--
Mark