I don't use Windows, so I can't help you on the escaping of the *, but I
often use propedit, rather than propset (partly because I can never
remember the order of the directory and the property value), so that would
be easy enough for a one-off solution.
Also, if you are using TortoiseSVN, can't you just right-click the
directory and set the property that way and avoid the command-line usage
You're just jealous because the voices are talking to me.