This is a feature of the Convenient Horses plugin, but it's really the only feature I like. Instead of using the plugin anyway or doing without it entirely, I'm thinking about trying to add this feature myself to the vanilla horses of Skyrim. The problem is that I don't really know how it's done.

Anyone have experience with this? Or maybe some advice or something? I'd appreciate it, even if it comes in the form of older threads with just a few clues or hints.