Although you can listen for document events, I don't think you can drop a component on to a movieclip and get the reference of the movieclip.
What you could do though is write a command that first stores the reference of the selected movie clip and then adds the component to the stage, with the mc parameter setup.
Here's a quick example using the Button component. The command get's the name of the selected mc then adds a button and sets the name of the mc as the Button name.
var doc = fl.getDocumentDOM();
var mc = doc.selection[0];//get the mc
doc.selectNone();
//add the component
fl.componentsPanel.addItemToDocument({x:mc.x, y:mc.y}, "User Interface", "Button");
//setup parameter
//use this if you don't know the paramater's index in the list
setComponentValueByParamName(doc.selection[0],'label',mc.name);
//otherhise you can get away with
//doc.selection[0].parameters[2].value = mc.name;
//returns true if the param was found and value was set, otherwise returns false
function setComponentValueByParamName(component,param,value){
for(var i = 0 ; i < component.parameters.length; i++){
if(component.parameters[i].name == param){
component.parameters[i].value = value;
return true;
}
}
return false;
}
Have a look at fl.componentPanel, ComponentInstance and Parameter to get a better picture.
HTH