Here are two pics from my former 01 X5. The supply line is just above the water pump pulley. I just unscrewed the plug that was in the manifold and screwed in the 90 degree brass fitting. At the bottom of the second pic you can just barely see the Y of the return as it enters the raw water intake hose.
"For every complex problem there is an answer that is clear, simple, and wrong." (Henry Louis Mencken)
2005 X2, Viper Red, MCX, Acme 1285, PPass, rear 750 sacs, KGB, IBS
(previous) 2001 X5, 1991 TriStar 190