Have you tried swapping the x, y values, such as (x1, y1) becomes (y1, x1) after rotation. I have never modified the hildon-home code, will try to implement some ideas.
How about a popup menu after installation congratulation you on installing the step 5/5 and then stating the customization packing can be installed now if needed? I think all the "extras" should be enabled by default... instead of enabling them after installation.