You will have thick areas around Graham summit (other than the road back towards Balsam Lake) but there should be a feint path to go through. There is some steep areas on the way to Doubletop too and I believe it might be nettle infested. I think the first time I did Doubletop, a friend and I did it as a super long dayhike. From biscuit brook, we hiked to Doubletop, went over to graham, then back to doubletop, then down through Frost Valley and then walked back to our car. It was like ~17 miles. There might be a small herdpath between Graham but it might not be worth it to really try to follow. Much like following the yellow blazes to DT from Biscuit Brook, it's faster and a lot easier to simply point yourself with the compass and hike. Definitely bring a compass with you, on all bushwacks in the catskills... Erh, on all bushwacks everywhere.. I use my compass in the ADKs too, myself.
Jay