I know today OOTB we have couple of ways generate the document from Word Template.
1. using CreateandMergeDocument feature using Silverlight.
2. using Docx4J to create a document from work template and return the URL. (without silver light)
I am looking toward the option 2 but mainly not the URL just the content after populating the data into the template and return as pvzStream or HTLM so that i can convert that and attach it to the case than the URL.