http://maven.apache.org/settings.html As per documentation the user specific settings can be either copied to the .m2 folder or under the maven installation. If a developer changes a machine or gets a new user id, such properties have to be copied manually to these newer machines.
Would it be possible to store user specific setting information in the repository itself (say SVN) and somehow have the mvn scripts load it on startup.
Nope, the whole point of having user settings is to store them outside the maven projects. There's nothing stopping you from creating your own svn repository and storing your configuration files there, though. You could write some shell scripts to bootstrap a new workstation from that repository, but it really depends how often you do this to make it worthwhile.
I would suggest that you setup your own repository such as Archiva, Nexus or Artifactory. Which will get your dependencies/plugins , then you can use mirror to specify explicitly just one repository to be used(the one you setup on your network). So whenever developer changes machine or dependencies are needed for multiple developers the internal mirror can be used as repo, your dependencies/plugins will download in no time to your local repository/ies
If the content of the settings.xml is not that user specific (e.g. for mirrors), you could store the whole Maven install in SVN with a customized conf/settings.xml and have the developers grab it from SVN to "install" it on a new machine as described in this previous answer.
If the content of the settings.xml is really user specific (e.g. it contains secret things like passwords), then it must be located in ~/.m2 and you will have to somehow make it available at the new location. If a developer logs on another machine, you could use "Roaming user profile". If a developer gets another id, then you'll really have to duplicate it. The technical solution may depend on the level of confidentiality required.
And if you have several developers sharing a userid but still need different settings.xml, then you'll have to pass it to Maven using the -s option. One could imagine storing these custom settings.xml in the project in that case (assuming it doesn't contain sensitive information). For example:
mvn -s settings-user1.xml <goal>