Using Adobe Digital Editions it is possible to download EPUB ebooks in PDF format from opened .acsm files, that act as some sort of ticket that validates legal purchase of a digital publication, which is what acsm to doc conversion more or less represents.
Once you have the ebook downloaded, you can easily convert pdf to doc using any tools available.
Open ACSM file Open DOC fileA set of tools for create, distribute, monetize and optimize publications for tablet devices