How itemRenderer works with flex "Stacked" charts? Can anyone refer me to a tutorial/sample?

Question

I want to render the colors in a "Stacked" bar chart using itemRenderer. I have a dynamic arrayCollection of objects (object contains 2 fields: type:String and value:long), I want to render the color according to the object.type value, each type will have a special custom color (texture). Can anybody refer me to a flex tutorial/sample where I can figure how itemRenderer works with "Satcked" bar Chart