Character at index of string? Finding which character is at an index like in Javascript charAt

I am trying to find the Character of an index of a string. The reason I am doing this is because I would like to break up a string. lets say every 5th space.. " " I would like to replace with a break. Because I can not find a width and text wrap with a text mesh.

Any ideas? I have been looking at this http://www.w3schools.com/jsref/jsref_charat.asp

ans so I have started to write something like this to test if it would insert the * private var myComment : TextMesh;

 function Awake(){
 
 myComment= GetComponent(TextMesh);
 }
 
 
 function Start(){
     AssignComment("This is some cool text because it is very long and I love it. you love it? yes you love it , its just great to have such a long commnet. ");
 }
 
 function AssignComment(incComment : String){
     var SeperatedString : String = incComment;
     var CommentLength : int = incComment.length;
     
 
     
     for(var i : int = 0; i< CommentLength; i+=20)
         for(var b : int = 0; b<20; b++)
             if(incComment.charAt(i+b)==" ")
                 {
                 SeperatedString.Replace(SeperatedString.charAt(i+b),"*");
                 b=20;
                 }
         
         
     myComment.text = SeperatedString;
 }