I found an example named PoiWord which genereated a WORD-Document (see attached file), so my question was if i can manipulate an existing Word-Document.
Guess you need to complete the code to support changing (if poi itself does support it) using java object.
Or write a wrapper for word-pois methods/object with java.
ms office files should be zip files with xml file content.
as example .docx can be renamed in .docx.zip and you can look at the files in windows explorer.