Having thought about this I am either going to make it clear what is happening here or make myself look like a complete pratt.....the latter is more probable
I hope I can explain this clearly and make you understand, I think I am correct in saying for you E & W would be reversed on this diagram if you are in the southern hemisphere (which I think you are?).
If you took the diagram below (reversed East and West)and put it in front of your dish this gives you the direction of rotation of the lnb for what is known as skew. Whilst obviously the arc of the geostationary satellites as viewed from earth is exaggerated for the purposes of clarity in this drawing this will give you the general idea. Thus from where you are the satellite that is directly due north of your position will have zero skew to the East the lnb rotates anticlockwise and clockwise for West. As to how that is calculated, I have not a clue, like I said my mount does it for me.
The second picture just gives you an idea of the actual angle of the signal path for an offset dish, hope this helps