Sadly, I'm guessing this will never happen because it will be an enabler for Bots...
Hmm...maybe I'm naive, but given how limited the API is for initiating actions without a user pressing a button or some such, how could you build a bot based on this? A keystroke generator outside of the game to navigate to a desired location while you get a snack? I'm probably missing something.
OK, I've given this some more thought. The method call I suggest, without any limitations, would certainly be used by someone to do something they shouldn't...no matter how hard it would be, someone would find it worth the effort. So...how about this?
Instead of a method, make it an event - LocalPlayer.GetInstance():Loca tionChanged(sender, args)
Limit the precision of the data...I think something along the lines of 1/2 of a ";loc"-style degree would suffice for most legit uses, but would make any botting quite difficult. I think that precision is low enough that even travel by fast horse wouldn't return coordinates often enough for botting, but is high enough to allow map projects to show a character location marker and for guides to get you close enough to see your goal. A random error could be added to the coordinates returned, within the range of precision, so the event can't be relied on as "the player just crossed the 0.5 degree mark" - it would then never return precise coordinates. Auto-navigating most any real terrain without more precise coordinates would be next to impossible.
Only fire the event when the player's location has changed according to the above precision, adding the error as above.
(maybe) Don't return the "h" parameter from "/loc". This would make botting even harder, and wouldn't hurt most other things. Waypoint would want it, but I think it could make due with calculations based on x/y changes for the most part.