Help with a drag and drop (again)

I am looking to implement something like this:

http://www.mundidesign.com/webct/webct.html

where there are many colour swatches that when dragged and dropped onto one of three targets the target changes to that colour.

So far I have been able to implement a simple drag and drop where one draggable object is targeted onto one specific target, but I cannot make several different draggable objects be dropped onto any one of several targets and I also cannot get the target to fill with the approprite colour.

I know it is probably something to do with SET.RGB but cannot get my head round how to actualy implement it.

Any ideas?