Answer:
Very rarely will a roof sewer vent need to be cleaned. On the occasion that you need to remove debris or a nest, the best way is to try a shop vac. Then you could try a hose to clear any other items down thru the drain pipe. These methods should be adequate to remove 99% of the blockages. Never try to snake a roof vent! There are too many dangers and problems that may occur from trying to do so.