That is correct. You can look at the cylinder by choosing the "Ring" option which will roll the flat plane in the X or y axis. To post this using a 4th axis you need to look at all the post options and find one that translates the rolled axis (Y lets say) into the "A" axis.
I used the post called "Gcode (Y->A)(in)"
See my post below.
http://www.cnczone.com/forums/showth...1&page=37&pp=5 (Building a CNC router)