By default item templates are rendered below item text. You can control the rendering location by placing the template inside a DIV tag and tweaking its CSS.

<ItemTemplate>
	<div style="margin-top:-28px;float:right;">
		<input type="button" value="Expand/Collapse" ID="Button1" />
	</div>
</ItemTemplate>

In this example the template is moved by 28 pixels by settings its top margin (the panel item height is 28 pixels).