I always figured it is what it is, I never tried or had a need to read it out loud, like most words when you're reading, you see it, you recognize it, it paints its pictures in your mind, you understand it (or don't and look it up) and go on. But if you need more Allen got the most popular answer, there are others.
Audio pronouniation in Italian here - http://www.forvo.com/word/aoxomoxoa/
Apparently, liked it's spelled, minus the first "A" - the title is pronounced "OX-OH-MOX-OH-AH". That's according to the audio version of the Rock Scully memoir, "Living With the Dead" (read by the author and former Dead co-manager himself)
But in this thread, someone claims that Rick Griffin, the Dead's main album cover artist, pronounced the "A" at the beginning:
"Saw an interview quite some time ago & Griffin pronounced it A-OXO-MOX-O-A ...long "A" sound in the beginning & short "A" sound at the end".
Now if I could figure what the heck Anthony posted .... LOL