My buddy does a trick with a caping knife in which he just cuts out a 3 inch hole under the tail and through the pelvis. I've never been able to copy it, so I end up using a zip saw to go through the pelvis.
I work loose all the guts from the top carefully working backwards towards the anus, carefully cutting the diaphram and any other membrane holding it all into the stomach/chest cavity. I tilt the body sieways and let gravity pull the guts out.
I use a very sharp knife and cut around the anus (from the outside) until I can pull the intestines (colon) loose from the inside and dump everything onto the ground. The bladder, I try and cut it loose from the inside and remove it without spilling any fluids.
Then I hang it, split the sternum, remove the esophagus and spray it down well with the hose.
At this point I remove the hanging tenders and get them onto the grill to eat. :-)