ASP.NET Form Field Security using Attributes

Question

I'm looking to implement something similar to this article:
http://msdn.microsoft.com/en-us/library/aa480723.aspx

One of the issues I have though is that I need to apply custom System.Attributes to the controls defined in a FormView ItemTemplate and EditItemTemplate. How can I modify the declaration of those controls or apply the custom attributes to those controls in some other way to implement granular, field-level security? (e.g. TextBox1 should be read only if the user doesn't have a particular permission)