I would like to know how i can easily use role based authentication to
enable or disable certain controls (e.g. buttons) in a windows .NET
application.

Anyone suggestions?

One approach is to perform a role-based security check in the
"VisibleChanged" event (or override "OnVisibleChanged" if appropriate).
You can then set the Enabled property appropriately.
In your Form_Load event you could iterate the Controls on the form and
attach the event handler.

You can assign roles to controls declaratively in code with a custom
attribute, and then use reflection in the event handler code to get the
attribute.