Creating a property of Linq.DataContext.Function?

[Andy B]

I am making a user control that needs to have a DataSource property exposed
to the pages that it is put on since the data source will be determined
based on what page the control is put on. The DataSource property I want to
create needs to accept a value of System.Data.Linq.DataContext.Function (it
is an sql function). Any ideas how to create this type of property?