As already said, Extract the DTMLRepoPath-0.1.0.tgz archive in the root of your Zope installation. It will put 8 files in lib/python/OFS directory, 4 overwriting the existing files, 4 of the (presumabley) same content with the overwritten files with ".original" extension attached. The "*.original" files are the "*" files come with ZOPE 2.1.2 distribution.

If your ZOPE is not 2.1.2 distribution or you've altered the 4 files(DTMLDocument.py, DTMLMethod.py, documentAdd.dtml, methodAdd.dtml) already, just extract the archive on the some other directory and see what I have changed & added in those files. If your ZOPE is older one, which only understands <!--#xxx -->: syntax, you must do so, since I've used <dtml-xxx > and &dtml-xxx; syntax. Just search for "kslee". I've commented with "by kslee" where modified.

Hope this can be a help. :-)