hi mate,
the best way around it i think if you have a manual is put it in 1st gear and put handbrake on and it should come loose quite easy,youll definately need a puller to get it off as its held in by a key,it will only go back on in one position to allign with the key so you cant get it wrong,just make sure you allign the marks on the pulley to the marks on the casing (check the 1st piston is at firing stroke) else it can be 180 out on the pulley and remove it.
youll have to put it neutral after cause you dont want it to move the crank,the best way really is lock up the flywheel on the gearbox side that way it definately wont move,if youve got an auto box its gonna be a pain in the ass.