H2EK is extremely stripped down compare to H1EK; Microsoft didn't really want people making custom maps, and hence stripped many features out (Some features have been restored by the community, although many features are still missing). H2 itself, doesn't even allow AI spawning in the Multiplayer Engine (people have applications to edit memory, to swap the engine temporarly to get some AI spawning in MP), and H2EK is only directly designed to compile MP maps.
Anyways, if you collect all the hacked tools, you can at least create a singleplayer map with Spartan and Elite AI, although they will not be able to freely wander the map; the information required to do so has been stripped. You can either have them stand still, or make them walk a set direction for a set number of steps. References to the AI are also stripped, meaning you cannot use scripts to refer to the AI later on (if they didn't strip this, you could of written your own AI pathfinding setup).
Look around here
, thats an entire H2V community. The tools should be available there, as well as the few people left who deal with H2V.