Is there a way to convert a 2d generic list to a string in unityscript

I have some javascript code I'm trying to convert that takes a two dimensional array and uses a javascript join to turn it into a string then splits the string to turn it into a one dimensional array. I'm converting this code to run on iphone in pragma strict so I'm using generic .net lists instead of javascript type arrays. Is there an equivalent of the javascript type of join for generic lists or maybe another way to do this.