Yes, it could be added to the board login as well as anywhere else, however, that would require much more work than the scope of this modification was intended for. I'm not even sure there's appropriate custom hooks, so there may possibly be yet more file edits.
So, while yes it can be done, it's really not something I'm planning on implementing nor describing how to do in any great detail, sorry. You best bet would be asking around in
Requests For Paid Services.