Most helpful Answer
There is a plugin called SCM Sync configuration plugin.
Original Answer
Have a look at my answer to a similar question. The basic idea is to use the filesystem-scm-plugin to detect changes to the xml-files. Your second part would be committing the changes to SVN.
EDIT: If you find a way to determine the user for a change, let us know.
EDIT 2011-01-10 Meanwhile there is a new plugin: SCM Sync configuration plugin. Currently it only works with subversion and git, but support for more repositories is planned. I am using it since version 0.0.3 and it worked good so far.