Custom Field filter on Magento 1.9 Admin Manage Customer page

[aizaz]

I have a custom field that is visible on Add new Customer and edit customer page. Its multi select field that allow to associate customer with different websites.

Now i want to use that field for filtering user when someone select website from droppdown on manage customer field.

How can i do that?

[Pronto]

There's a pretty neat extension that allows store manager to update admin grids. I think this covers what you want to achieve:
https://www.magentocommerce.com/magento-connect/enhanced-admin-grids-editor.html