How do I add nekudois to a letter in illustrator?
How do I add vowels to hebrew in Ai? 
I think you generally need a plugin
here is a post I found
You can type Hebrew nekudos very easily and quickly, by the plug-in Rav-Nakad - תכנת “רַב נַקָּד” – דגל ניקוד .
All its interface is in Hebrew, but here is a video about how to use it with InDesign: רב-נקד גירסה 1.12 - כעת מנקד בתוך אינדיזיין! - YouTube
Rav-Nakad is free for one week.
Hope it will help,
Thanks a mil!