If you mean getting the gearbox input shaft through the clutch and spigot bearing on the end of the crank-shaft, yes it can be a problem.
I can't give any real tips on this as it never was that simple for me. Only pointer I can give is the need to use a clutch alignment tool and be very fussy about getting the plate absolutely centralised.
If one has a spare gearbox shaft, you can use that, but an adjustable clutch alignment tool is not that expensive.
My experiences were ages spent moving the engine around followed by the two bits going together so quickly one wonders what all the fuss was about.
