it will go inside the the following section:
Code:
<PanelFile ID="ID_UISkin_Toolbar">
<Element ID="ToolbarField" X="0" Y="508" Width="1024" Height="200">
.
.
whole bunch of stuff for other parts of the toolbar
.
<Element ID="Toolbar_WebstoreButton" X="???" Y="???" Width="1" Height="1"></Element>
</Element>
</PanelFile>