Hi there JWest, and welcome to this board!
I'm probably not qualified to instruct on this matter, so everyone please feel free to correct me.
Gokyu, the fifth pin - normaly I train this as a variant of ikkyu against e.g. tanto Yokomen. If the yokomen comes from ukes right hand, then enter fast to the left and block the slash with your left arm. In the case of ikkyu you follow up with your right hand of the outside of his right arm and control. Now insted you emediatly grip with your right hand ukes right wrist from the inside (in order to control the knife hand), and proceed to do as in ikkyu but with the grip tightly hold all the way through.
A note - in our dojo we only practice this as ura variant.
Rokkyu, the sixth pin - Another name for it is Hiji shime i.e. elbow lock. If we use a right hand tsuki as attack this time, then (nage) step of the line to your left. Now imagine you're holding a cylinder (in the way so that you can roll it!) between your hands, your left hand on top palm down and the right hand holding the bottom palm up. Now imagine rolling the cylinder (the left hand in a forward motion and the right hand in a backward one). Now replace the cylinder with ukes wrist and do the same as the stuki comes. As you do this, let your left arm (from the elbow down) connect with ukes arm, hence locking ukes elbow. Now in one motion guide ukes arm forward, down, right and up (from ukes perspective!) as you do a tai sabaki with your right leg. Phew! hope you understand that one better than before, lol.