I use Safe n Simple stoma wipes to clean off the dirt. Its also nice and easy to carry in an emergency bag in case you at a place with no water.
At home I also just use plain ivory soap and warm water around the skin. I use a paper towel cut into 4 squares so I can just toss out after the use. ! square I wet and rub soap on it and two squares I dampen with warm water for rinsing. Additional squares are used to pat dry and hold around my stoma if it get a bit active during the change.
www.sns-medical.com/newone_009.htm