So i'm making a cake for a friends birthday, i was playing on make a Neapolitan cake with 6 layers. I've never assembled a cake of that height before and was wondering how hight the cake should be before I put in support? Also kind of support should i be using? Please help!! 

The rule of thumb is support anything over 4" tall.  I'm assuming each layer is 2" tall then your finished cake will be 12" tall?

That is going to be a nightmare to transport! :(  The kind of support used it up  to you -- maybe those hollow plastic tubes Wilton has?  This might be a time for SPS - get LeahS attention for more information on those.  It will give much more stability to such a tall cake.

Just go with 1/2" (or 3/4") high layers in the neopolitan flavors.      (Kakeladi, I can't imagine she was talking about 2" high layers...)

You'll end up with a cake that is about 6"+ tall with filling and frosting.  I'd recommend two wooden dowels driven through the cake from top to bottom, about 2 inches apart.  You may wish to place the cake on a foam core cake board (covered with fondant or Fanci-Foil) and then you can actually drive the sharpened dowels down into the foam core to provide extra stability.