The PureMVC Framework Code at the Speed of Thought

Hi,

I'm redesigning in  PureMVC a rather "monolithic" app I've developped to learn Flex. I'm now refactoring the harder part :
my app is using an advancedDatagrid with several editors.
One of these is a complex one (multi state, multi textinput, ...). On one state, when the user has entered a name, I have to check if the name exists in the database (no way to cache data before, there are 500 000 names), via a remote object.
The database access is currently done in the ItemEditor. The ItemEditEnd event of the datagrid verify is data has been checked and allow closing of the editor or not.
How can I do that with PureMVC ? Do I need to encapsulate a lot in the editor or use a mediator ? How to instanciate it then ?
Is there any demo on this subject ?