With the current implementation of tunnelled svn:// access, it's difficult to control the authentication, port number or other arguments to an ssh tunnel. The most obvious thing to do is to add a username/port to the svn:// URI on the commandline, but these attributes are ignored in the current implementation. I'll attach a couple of patches which add support for ssh/rsh/rlogin arguments by honoring URI username/port attributes or by adding two svn-tunnel-* configuration options to the group configuration. The latter is arguably more correct (since it's the tunnel's parameters being given, not those of the repository), but the former is rather more convenient and matches user expectations.
Original issue reported by devin