I am surprised that the GASKET is leaking. Are you sure that there is no crack in the manifold.
If the problem is the gasket, the only "trick" I would know is that if the stud comes out instead of the nut, carefully remove the nut from the stud and replace the stud in the head. This will make it much easier to put the gasket AND manifold in place.
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in