Head gasket replace flywheel question

I'm doing a head gasket replace and a bit deep in it. I didn't see the part early on (gasket masters vid) about loosening i the flywheel/harmonic balancer and now I am at that stage. So I am wondering if anybody has ideas or been in this situation to help out. Thank you!

 

Yes the one on the passenger side. The gasket masters video does it near the beginning with another person that starts the car to crank it open. I am wondering if I need to use some kind of wedge or breaker bar to hold the wheel from spinning (without damaging wheel) while using the impact wrench?

In the Lets Drift Media video he takes it off around the stage i am in just with the impact gun but said something like "i already have the timing set at 2 oclock.." then just zips out the bolt . He's blocking the shot so I cant see how or if he is holding the wheel with something.