Hi Mychal B
This is what vaguely springs to my mind. This may not work the way you desire, but each significant height within your level can be given a different container, and if necessary a zone.
The AI system leaves you responsible for Y axis movement (besides ducking); so; when you want your entity to go up the slope, you change its current container. You also change the entity Y position to that of its current slope height; using intersect object or physics ray trace commands; based on its position from the slope.
If you do not change its container, the entity will think that it can still walk around via your waypoints (which may be set automatically providing you are using the complete obstacles procedure)
Zones can be used to run certain functions or sub routines per position on that slope, in relation to the positions of other entities or players in their own zones; using [AI Get Entity In Zone] or [AI Get Player In Zone] respectively.