I say Al-dyew-in. I lay no claim to any knowledge on this at all though
[Edit] changed the spelling as it's how others are describing it, and it's the same as what I was going for (so that there's no confusion)
More like, AL-Dew-In.
:P
Most Elder Scrolls naming is said how it is spelled. In the imperial sense. The most common vowel soundings.
A = ahhhh
E = (the Letter)
I = eye, OR as in if, when used in conjuction with another vowel, such as U
O = oh
U = You
There are other rules, of course, but Highschool English teaches how to read new words.