Add a trademark to a word everywhere on a site
You can use "String Overrides" (http://drupal.org/project/stringoverrides) module to accomplish what you want to do and it will work even if JavaScript is disabled and the changes will be cached as well by the Drupal cache.

Note: This will work with content pass by the t() function, if you have the word hard coded on the theme or module it will not work. Also it is CaSe SeSiTiVe.