I should think that Redhat 7.2 would support the SB Live series.
Have you tried to manually load emu10k1?
and see what messages you get. Also have a look at /var/log/messages.
I'm not sure if you should go ahead and create /dev/dsp yourself or the system creates it for you when sound has been setup correctly. You could search at Google to find out what major/minor numbers are required for dsp and create the character device manually.
mknod /dev/dsp ## ##