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 JavaScript String charAt() Method

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;
}

A string is an array of chars.

if (incComment[i+b] == " "[0])