You could rotate the cam gears by hand. Or what I do is just rotate it with either a boxed end wrench or turn it using a socket via the nut on the cam gear.
Its going to be kinda hard to slip on the belt and keep all pulleys at TDC. But on 4th gen ludes the cams have a small hole right on top in which you could stick a 5mm rod to keep it from turning. I suggest you do this.
email me if you have further questions:
arax@mail.com