What I used was a six rung folding ladder from West Marine . . . think it costs just over 150.00, but of a very high quality.
I didn't mount to the genoa track, but instead secured the (2) SS clips (supplied) to the top of my teak toerail. We have them on both sides for flexibility. Works very well and sits well below the water surface for easy egress . . . great since I scubadive often from the boat.