EDIT 9th JUNE 2012 : FIXED
First, this little exploit won't do all the job for you, but it helps a lot for kill him.
First, a summary of the major events of the fight :
The first important thing is that he always launch 2 nova in the fight, and always at the same % of his life. If like me, the nova one shot you, when you know that, you can counter it easily ! (For Demon hunter : Be ready to use your smoke screen !)
An other important advice : NEVER stay for too long in a straight line behind any monster in the fight, or he will charge you and pwn you !
Oh I already ear you "WTF THATS NOT AN EXPLOIT ! THAT'S JUST A GUIDE GUY !" Wait wait, the little exploiting part is coming !
There is few placement that permit to use Tyrael for block Izual.
You can block him here :
Explanation : He want use the shortest way for come to you, but you'll use Tyrael for block the narrow passage where he need to go for use the shortest way between him and you. (I hope that my english is not too bad, and that you understand the idea ^^ )
If you block him at the place where I blocked him on my screenshot, when mobs spawn, they are always blocked too and you can kill them easily.
I put a little video that I've just done for that you see how powerfull that can be :
For Demon hunter who want my build : Demon Hunter - Game Guide - Diablo III