Add a scripting command that for a given parameter in range [0,1] yields a point on a given rope. Example:

_pos = _rope ropePoint 0.5;
_posATL = _rope ropePointATL 0.5;

which would yield the position _pos at 50% of the rope's length, with 0 being the origin of the rope, and 1 being its endpoint.

Reasoning:
In absence of "real" fastroping (which would be preferable but probably much more work-intensive), this would allow easy fast roping scripts, as well as rapel ability and things like Grappling hooks and Zip lines.