Passing form-based POST login to leech software?

First off I just want to say I wouldn't post here if what I was doing wasn't totally legit. I do need some help though or at least pointed in the right direction. I have the login/pass that our website admin has issued us. However, the problem we're having is that we don't have a contract with him and he has refused to fix the coldfusion scripts that let us run our CMS, going on several months now.

So all I have to go by is what I have, a proper username and login. The main thing is that we can't get our data from him because if we cancel with him he'll delete the account and all the work and contacts we have already. We're transitioning over to a different CMS now. So I've leeched the rest of the data accessible publicly and backed it up. But now as I'm trying to get our internal stuff I'm finding it difficult to have our leech software authenticate with the POST data of the form-based login.

Is it possible to pass a cookie to our specific leech program or include POST data in the starting address of the leech program?

This isn't "hacking" by any means, just an interesting conundrum and problem. Security-wise, when I transition over to our new site I fully intend to implement anti-leeching PHP scripts.