Change the timestamp of an SVN revision

Change the svn:date property of the revision:

svn propset -rXXX --revprop svn:date "2008-03-10T03:00:00.000000Z" repository

Or using TortoiseSVN, Show log -> Right click on the revision -> Show revision properties:

You will need for that the pre-revprop-change hook, a empty shell script or batch file will do the work.

The date/time is a property of the revision. Figure out the revision number (or use HEAD), and modify it with propset or propedit and --revprop.

svn propset svn:date 'YYYY-MM-DDTHH:MM:SS.MMMMMMZ' --revprop -r HEAD /path/to/wc/file

You'll have to play around with it to get the right combination of settings. You can also look at the Red Book, under Advanced Properties. (I linked to 1.4, adjust to suit your version).