Tinderbox to Word
If you'd like to use Tinderbox to draft a document that's destined for Microsoft Word, consider exporting to a single big HTML file. Though Word's HTML export is problematic, its import is clean -- and it's smart about things like heading styles.
Just export to HTML, import to Word, and apply your company's or your publisher's stylesheet. This will get better, once Word's highly-touted XML interchange format becomes real, but it's very useful right now.