a set distance from the hinge line right?
Create a 2d line at the distance you want from the hinge line and then drape it on the og and then add the draped line to the corridor as a reference line and then make a connect instruction from the hinge to the ref line - the slope will vary but it will tie correctly - i assume that is what you are asking?
You can probably do it in the corridor if you do an offset elev for the distance and 0 elev and then do a tie up or down to compute where the tie is on og Nd then do a connect from hinge to the tie line that you just computed. Leave the offset elev and the tie up or down as no material layer and then make the connect part of finished grade
Alan