When creating the XML script use the insertBeforeMso="TabHome" parameter when creating the tab e.g. something like:
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
<ribbon>
<tabs>
<tab id="CustomTabMyTab" insertBeforeMso="TabHome" label="MyLabel">
<group id="InvGroup" label="My Template Name">
see
http://gregmaxey.com/word_tip_pages/...bbon_main.html