On our network client machines use "identd_200.exe" for each machine to get Internet access though the use of our log in names. I have a user/passwd for my server to access the internet...
Without knowing any technical details of what identd_200.exe does, it won't be possible for you to access the Internet from SME server.
My guess however is that identd_200 is an rfc 1413 server:
http://en.wikipedia.org/wiki/IdentYou could try using a custom template (search here) for /etc/oidentd.conf so that oidentd on SME server identifies squid as being your user name, when your proxy asks.
This is probably more trouble than it is worth, and you should try our SME server on a less locked-down network.