Sposed to have an engine holding tool, some stick a penny between gears, I dont like that & I used a folded piece of leather.

Also, getting the nut on & snugged( IIRC) requires something to hold the cage that the clutch disks sit in, but an impact will run it up snug, then you can torque it from there.Others may have a better answer, but I did the cam chain this way, & ( Again, IIRC) the clutch could have been replaced during that procedure with no further disassembly..