Use SVN outside of Maven. Maven can use SVN as one of of it's source
control management providers, but that's really just for build and
deploy tagging, pushing, etc.
If you just want to add some files to SVN, or import a project, use
the SVN commands on their own.
http://svnbook.red-bean.com/
(And neither of these is really a GWT-Maven topic, if you need more
support you might try some general Maven or SVN mailing lists.)