If you want to make an aimbot and you want it to be as easy as possible, you should probably try looking at the CreateRemoteThread and ReadProcessMemory APIs. That's really all it takes.. well, almost.
Actually, I believe high6 posted the source code of his auto-follower somewhere in this section somewhere. All you really gotta do is update it and replace the jump function with the UseXYSkill (that's just what I call it, the one for casting Toxic Fog, FB, SS, etc.) and some other minor adjustments perhaps and you're good to go.
If you're interested in C++ (I tihnk it was), you should have a look at that.