I've just done the manual conversion on my mv6 and although it's straight forward enough there is a lot of bits to be changed. Ideally you would have a donor car to sit beside your one but I sourced most of the parts from a local breakers yard. You will have to remove the gearbox, propshaft. torque converter, flywheel, brake pedal box, gear selector and associated bits of trim, ATF pipes running to the radiator and the plastic bung covering the hole for the clutch master cylinder. Then replace all those bits from the donor car. You also have to buy a spiggot bearing for the rear of the crank as automatics don't have one.
I did the lot in a weekend and a couple of evenings and the car feels so much the better for it. The only problem I haven't addressed yet is the MID which displays AUTOMATIC GEARBOX when I first move off after starting the car.