I want to create a function in my template.php that will set a different banner for certain pages by modifying the background property for the div with jQuery.  The jQuery is pretty easy (I would just add it using drupal_add_js()), but what I can't figure out is how to call it from template.php.  Can I just create my own function in template.php that calls drupal_add_js()?  Or do I have to use a hook?  I need to have the current URL available to the function.  My first thought was to use a preprocess hook, but it seems that the preprocess is for adding variables, not this.  If I wanted to write a module I could do something like hook_init, but I don't want to have to do a module for something small like this if I don't have to.

Thanks

Steve