How to fire event of GridView outside of GridView

Question

How to fire for example OnRowUpdating event of GridView outside of Gridview by external button ? I have 2 buttons for update: one is in gridview in each row which fires event OnRowUpdating="MyGrid_RowUpdating" - works fine; and I have stand-alone OK button (<asp:ImageButton ID="imgbtn_UpdateSomething" runat="server" ... ) outside of Gridview which I also want to generate event OnRowUpdating - I have an complicated event-handler MyGrid_RowUpdating (in which I need to use e of  "GridViewUpdateEventArgs e"), which I want to use also for my external OK button.. Is it possible ?