How to override jquery update preprocess page
JSAlter module for D6 should solve your problem..

Project page says


  This module will not be ported to Drupal 7, because Drupal 7 core
  natively includes a hook_js_alter(). Note that the signature and when
  the hook is invoked is slightly different in Drupal 7 core than it is
  in this module.
  
  This module adds a hook_js_alter() hook that other modules can use to
  modify the javascript that gets output to the page. The module
  provides no end-user functionality, but other modules can use this
  module as a dependency. Check out the JS Registry, JS Debug Helper,
  and jQuery Form Update modules for examples.