[1.9] Layer renderer

I been looking into how render over the top the player, and the way to go seem to be adding an layer to the player, know I have found an add layer method but I am thinking that will put at the top of the and get render over armour but I want my, my layer to be bottom must layer, after the player's skin. I have looked into this and seems I need to make my own layer, which I have done and I even added to the player in on player render event although, I think it may be better on entity join world, and in player render event update texture if needed, I am unsure how it works I am unable to find any good examples, the texture I want to load is an shirt with use Steve as base with the rest transparent but allows server overs to do maybe prison cloths, also now I think I will need Alex base model as well. So I understand I need bind an model to my layer not quite sure how to do that, or bind the texture to the model, or how easy it will be for the texture to be changed live, if any one knows an good layer renderer explain that is 1.9 completable, I would much appreciate it.