The dung and charcoal are serving the same purpose(adding body to the mixture) so you only need to use one of them. Bees wax will make the pitch glue less brittle.
My mixture is about 1/3 each pitch, finely ground charcoal and bees wax(maybe a bit more pitch). You can play with the ratios to see what works best for you and in your climate.
I start with hard, brittle pitch, melt it and add the bees wax and charcoal and blend them all well. When ready I dip a stick into the mix and immediately into cold water and repeat until you have a nice size wad on the end of the stick. These "glue sticks" are handier to use and convenient to carry in your day pack for in field repair.
The cool thing about pitch glue is if the point loosens or becomes untrue just heat the stone point up a little, straighten the point and let the pitch set again...good as new!!!