Pass parameters to an ExpressionBuilder

Hi,
I have a custom ExpressionBuilder in whixh I'm trying to add a list of optional parameters. My methid would be declared as follows:
public static string GetResource(string expression, params object[] parameters) { }
The way I'm calling this method from an ASP.NET page is this at the moment:
<ext:Button ID="btnEdit" runat="server" Text="<%$ AppResources : edit_text %>">
Does anyone know how to perform this method call, but using optional parameters?
Thanks in advance,
Dominik.
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