Quite easy really once you know how. Go to the top level of your checkout directory. Click properties, and select the subversion tab. See if svn:keywords is added - if it isn't then add it and in the value put the keywords you want to add. If it is there then just change the value. If directory click the recurse option and it will set the whole archive.
svn:keywords Date Revision Author HeadURL Id
Useful article: http://svnbook.red-bean.com/en/1.1/ch07s02.html