How to set the backgroundcolor of a datagridcolumn

you can create a movieclip with that background characteristics you want, assign it a linkage and a class.  its class file should look like:

class CustomColumn1 extends MovieClip {
    var txtField:TextField;
    function CustomColumn1() {
    }
    function setValue(theValue:String, theItem:Object, selected:String):Void {
        txtField.text = theValue;
    }
}

and use that movieclip's linkage id in:

yourDG.getColumnAt(i).cellRenderer = "customColumn1ID";