This isn't tested!!! But you may be able to do something like:
edit /login.php
at line 26 change the existing code:
if(($user=Client:(trim($_POST), trim($_POST), null, $errors))) {
to
if(($user=Client:(trim(str_replace('#','',$_POST)), trim($_POST), null, $errors))) {
p.s. its been a while since I used str_replace so I may have gotten it a little wrong. You may want to look it up. :) But this should point you in the right direction.