to set custom variables you can use the javascript API eg.
piwikTracker.setCustomVariable( ...
then in JSP you simply print out the login name to generate the right JS code. (make sure to espace the quotes in the value being printed)
piwikTracker.setCustomVariable( ...
then in JSP you simply print out the login name to generate the right JS code. (make sure to espace the quotes in the value being printed)