Rope Swinging Physics for Mod

Hi,

I am currently working on a rope swinging mod that allows a person to hook onto a fence post or a stone wall (or any special block), and my goal is to get the player or effected entity's movement to physically swing back and forth while in midair. There are options that allow procedures to be made with player directions and movement, however how would I be able to implement; if anyone has any ideas on how this can be accomplished or any ideas for starting this procedure it would be greatly appreciated.