I did write something like that a long time ago for ms source safe, but that was back in 1999-2000, and I don't have that code (it was done for my employer at the time)
I made a pattern skin for trac though http://develop.twiki.org/trac/timeline (login with your TWiki.org user and password)
or, see http://trac-hacks.org/wiki/TwikiNatSkinTheme and http://trac-hacks.org/wiki/TwikiPatternSkinTheme for a part of the work that I have pending final upload for TracOnTWikiContrib - which links TWiki and Trac's users.
If you really want to browse your svn from TWiki directly, there are TWikiStore possibilities - Crawford and I once started the SubversiveStore - but its not been tested much and is mostly for read only usage from memory.
-- SvenDowideit - 29 Jan 2008