need serious hook help

Hi, I need fairly advanced help. Great if someone here can answer, but is there a different place I should be looking/posting? Seems like my more technical questions go unanswered. Thanks either way! Here’s what I need to do:

Currently, when the default category widget is set to display as a dropdown (select) menu, the menu jumps to the user’s selection using javascript. There is no GO button. I need to remove the javascript and add add a GO button <input type='submit' value='GO'>

I can see WHERE this needs to happen, but I don’t know how to hook into it (I don’t want to alter the core files). By the way, I am doing this to make the select menu accessible.