Since I was a kid I've been hearing it as something like "Yaz Larm Ei" in my head. I'm fairly certain that isn't it. I think it's one of those silly names that's not really meant to be pronounced outloud, like "Slartibartfast" from "Hitchhikers" (Fun fact! Douglas Adams' named him that because he was being mean to his typist.)
The cousin who got me into HTTE pronounced it "Yass-alamiri." I think the Y is probably supposed to be pronounced "ee" like in Spanish, especially given that singular ones are always described using "an ysalamir." That makes more sense phonetically if the Y is a vowel sound.
Not pronunciation, but I always forget the correct spelling for "Pellaeon". Not sure if I got it there. I'm sure Jello could teach me how to spell his name, if I asked nicely.
No idea why but I always pronounced it Yeeslamary. I know it is no where close to right but when I first read Heir in my youth it was just the war I read it and now I'm so used to it I can't change it to anything else in my head.
Coop preëmpted the post I was going to make, and Uli correctly channeled me here so I feel as if I have nothing to say. I guess I could reveal the hilariously bad pronunciations I used as a kid -- but nah.
Man, teenage me had a whole litany of screwy pronunciations - kor-OO-sent (Coruscant), jay-SENN (Jacen), AIR-iss-EYE (Erisi), seh-bOWth (C'Baoth), huh-PAHN ("Hapan")...
Semi-officially C'Baoth is pronounced "suh-BAE-oth" Handy Link here: http://borkweb.com/story/star-wars-pronunciations - FWIW!