This has been an ongoing issue for quite some time for me with the PMDG 777-300ER. No matter what airport I use, the jetway when connecting to door 2L it connects far too high leaving the door exposed.
My gsx.cfg file parameters for Exit L2 are:
[exit2]
pos = -1.30 15.49 2.07 0.00
code = (L:7X7XCabinDoor2L,number)
name = L Entry 2