You'll need to compress the belt tensioner to get the belt off the pulley and back on when you're finished.
The crankshaft pulley bolt is bloomin' tight. I found the best way to shift it was to get someone to jam on the brakes and put the car in 5th gear to prevent the crankshaft from turning, then use a long breaker bar and socket. I think the bolt is 27mm, but am not sure.
The bolt is indeed 27mm. In case the info has become buried, I'd vote for the "Home Valet" electric impact wrench from Costco (or similar). The one I have cost £12 and claims a max torque of 339Nm.
Without getting into a debate over numbers versus real life, my experience is that it took my crank pulley bolt off with ease and I challenged it even more at the weekend with a 10 year old Volvo front drive shaft nut @ 36mm AF. Volvo torque spec on this is 120Nm stage 1 followed by a further 120 degrees for stage 2.
Took about an effortless minute to get off which included some time to plug it in to my 12V pack and fit the socket.
When it came to retightening, I struggled with a 2' breaker bar to make 120 degrees.