Change values in restyled usercontrol

Hi, I have a UserControl ("RecordNavigationControl") that I have added to a restyled DataGrid (i.e. the UserControl is part of the DataGrid.)

The DataGrid style is stored in a ResourceDictionary (customDataGridResourceDictionary.xaml). I can detect events as per my previous post: http://social.msdn.microsoft.com/Forums/en-US/c2a6be96-85d1-4a15-9c2d-c7b32712b585/capture-usercontrol-routedevent-wrapped-in-style

I now want to get at the controls in the UserControl (to dynamically change TextBox values and Button IsEnabled state) but I don't know how to get a handle to them (or to the DependencyProperties I've created in the UserControl).

How can I do this?

Thanks,

Graeme.