I guess you can always try this and see what happens. I just downloaded the old code, and replaced the list of sites it should run on with IMVU.com
// ==UserScript==
// @name auto-fill captcha
// @version 0.1.1
// @namespace http://herecomethelizards.co.uk/mu_captcha/
// @description Auto-fills the megaupload captcha and auto-starts download
// @include http://www.imvu.com/*
// @copyright 2009 Shaun Friedle
// @license GPL version 3; http://www.gnu.org/copyleft/gpl.html
//
// ==/UserScript==
Maybe it will work, maybe not.