I don't have a VB.Net sample handy, but here is some C# code.  I assume you are wanting SetHandler to use events in Markup:

/*

Your class needs to implement the IDispatch interface.

You need to add "using System.Runtime.InteropServices;" at the top of your file and "[ComVisible(true), ClassInterface(ClassInterfaceType.AutoDispatch)]" above your class declaration.

        public Form1()

        {

            InitializeComponent();

        }

            Label1.Caption = "<TextBlock>Click <Hyperlink Tag='This!' Click='Hyperlink_Click'>this</Hyperlink> or <Hyperlink Tag='That!' Click='Hyperlink_Click'>that</Hyperlink> link.  (Shows how to handle Markup Events)</TextBlock>";

            Label1.MarkupContext.SetHandler(this);

        [ComVisible(true)]

        public void Hyperlink_Click(XtremeMarkup.MarkupObject Sender, XtremeMarkup.MarkupRoutedEventArgs Args)

        {

            try

            {

                XtremeMarkup.MarkupHyperlink Element;

                Element = (XtremeMarkup.MarkupHyperlink)Sender;

                MessageBox.Show("Clicked: " + Element.Tag);

            }

            catch

            {

                MessageBox.Show("Clicked");

            }

        }