I was recently talking to Emirates Call Centre about seat allocations and the agent informed me in future if you insert in your seating preferances in your Skywards account then it will auto allocate if the seat is availible prior to booking. This will work on all economy saver and special tickets where you pay for the privilage of selecting after purchase. As the agent put it its the only "loop hole thats open"

Its not useful for me right now but may help others, so in simple insert preferances and then book. Providing seat is availible it will auto select