its not particularly hard, just box is heavy and space is tight. apart from the obvious bits to unbolt, what you do is rotate the box so the diff is pointing straight up, then drop it out from underneath. I found it helped to lower the engine at the gearbox end while its still bolted up, then unbolt the 2 brackets from the box before trying to remove it from the engine. Oh and dont forget the tin shield underneath between box & sump, and the other one round the back just above the driver side driveshaft
tip for reassembly, get the driveshafts in position as soon as you can, if you arn't careful they end up trapped below the box and they wont go back into place! alternatively you can unbolt the balljoints from the bearing carriers and then you can swing the struts out a bit to give you room to faff with the shafts.