Hi,
in the current version of PivotX (SVN revision 2404) there's no 'makeLink' hook in module_tags.php function tagLink(). Hence rewriting of tag links is not possible.
However this feature can easily be added by copy/pasting the code from module_parser.php. I'm attaching a patch. Can you include this in the official version?
Jan
EDIT: Attachment upload failed. Here you go: http://www.spacezone.de/download/pivot/module_tags.php.diff