Camera Rig Rail: How to set current position on rail in BP

I’m trying to create a camera rig that changes the current position on rail of the camera rig rail when I move my mouse left or right. I have the Mouse X event and a reference to the Current Position on Rail, but I don’t know where to go from here. All my searches turn up with Sequencer information but this is a gameplay camera controller, not a sequence.

Is there a way to do what I’m trying to do, or should I be going about this a completely different way?