Being that it's private property (and clearly marked as such), I would prefer to not see or hear of anyone using it. The gate is there for a reason, as are the road signs down below. With as many issues as we've had with people cutting Barr, littering, doing stupid stuff and getting hurt on the Incline and Barr, why take the risk of ticking off the property owners?
Just do it from the trailhead on Hydro. It's still quality training and doesn't really change anything in terms of the course.