Why would you build a tool for that, when Word already has a built-in comment facility?
You can get code to do this for Word's comments, at: http://answers.microsoft.com/en-us/o...3-3131ab68809c
Perhaps you could explain why you think you'd need to recreate the document. Sure, you'd need to update the workbook, but why recreate the document? Surely you'd simply add the comments to the existing document, rather than making another one?
Instead of re-processing all documents, the only ones that would need re-processing are those with a save date later than the last date you updated the Excel workbook. Having identified those documents, it then becomes a matter of deleting any existing comments for them, then re-populating the workbook with the new details. Quite straightforward, really.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]