Harmonic Balancer Bolt

Trying to remove bolt off of Harmonic Balancer for crankshaft sensor replacement....Is there any other way to keep the crankshaft from turning, other than taking off the Flywheel cover and wedging something in there to keep it from moving....?

Thanks

When I don't have access to an impact wrench- I merely set my breaker bar (with the socket on the bolt) against the frame- and then hit the starter- that will spin the bolt loose very easily- when tightening the bolt I will put a set of vise grips around the teeth of the flywheel so as not to damage the teeth- there are flywheel holder tools available though...

Was finally able to remove Harmonic balancer off of my 1990 88....The bolt was almost impossible to get off. My neighbors air wrench would not budge it...
I did locate the flywheel cover, removed it and secured the the flywheel as suggested. My neighbor used a breaker bar and finally broke it loose. Harmonic balancer slid right off. I then replaced the crankshaft sensor....Problem solved
Thanks to this forum.