as far as i know there is not a specific wiring diagram just for the stereo, the wires for it are included on the diagram for the entire cars electrics, do a search, the button to search is at the top of the page, below the silver antrx banner, in a little row which includes a home button, a help button and a search button and a profile button, a calendar button, and a logout button, the search button happens to be the third button from the left, click on it then type in wiring diagram then press enter, and you shall find a thread that should include a wiring diagram somewhere in the search results page
sorry i couldnt be more helpfull
good luck with the install, have a look around the noise section if you need anymore info or pics of others installs for ideas, i would like to see pics of the install in ur mates car when its done if possible