I have not investigated this in depth yet so take it with a grain of Sodium Chloride. According to the 2008 API docs, the functionality of Apprentice has been rolled into the Inventor Type Library. The docs tell you that Apprentice is still supported but will go away in the future.
I too have a rename parts/assemblies routine (stand-alone using Apprentice though) that works unmodified using 2008 and Apprentice. It has been my plan to try this as an add-in but I can
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Robert A. Williams
http://www.leacar.com
"Gentlemen...you can't fight here. This is the War Room!"