dezinerite, all you need are the input names from the current login page, then rewrite a form with those same names, and setting the 'action=' tag to the current login URL.
If the current login does use some kind of image verification, it may still be possible to utilize that.
If that doesn't make any sense, can you post a link to the page where they currently log in to their mail? Or PM it to me if you wish. With that i can grab the input names from it, and create a new html form for you.
Let me know if you haven't fixed this already.
-Rhett.