Just had to jump my 2008 R CDI... the negative connection point is a 3/8"ish pin that sticks in toward the engine almost inline with the hood strut just below the weather strip. Run your hand along the inside of the weather strip at that point, you'll find it.

Paul

__________________
as ever
Paul

1989 560SL
1987 300SDL
1987 300TD
1983 BMW 633CSi
1972 280SE 4.5