This proposal actually addresses exactly that problem. The dangly end of this thing down around GSO will not actually be in orbit at GSO. Rather, it will be hanging, stationary, at that point. In other words, you don't need to get 'into geostationary orbit.' Rather, you just need to lob yourself up so that your apoapsis is as high as GSO. Once there, you hook onto the little eye loop, or whatever fancier attachment system they devise, and wait to be pulled up to the Moon, more or less.
The key thing here is that you don't have to expend all the delta-v to get into GSO, but rather just enough to lob you to height. This, in itself, is a tremendous savings, given that you're shaving velocity off of a very large delta-v, where the penalties from the rocket equation are most severe. However, even if you only got a free ride from actual GSO to the Moon, it would still be an important savings.