FreeBSD-Server in a Windows NT environment

Hi

First of all, I am not sure if the technical terms which I am going to use in this post are correctly translated to english. Sorry.

I am running a FreeBSD server in my company inside of a Windows NT network. The problem that I face thereby is that every Internet traffic must go through the company-proxy. So at the moment, freebsd has no inet-connection and is therefor not able to get the desired ports. Now my first problem is, that I don't know where to tell the server that it must use this http-proxy. Secondly I believe that only clients who logged in into the NT-Domain have the permission to use the proxy (what you do when you login at the startup of windows). So I would like the freebsd to fake a NT-login in order to access the correct domain and thereby gaining privileges using the http-proxy.

I hope this wasn't too confusing...

Thanks in advance