I find this extremely concerning. I just purchased a microcell yesterday and was told that you can setup a proxy by AT&T IT folks.
Are you certain that there's no way to put in a basic proxy .pac file? Most businesses have a proxy so I find it hard to believe that htey market this for business and do not have a mechanism to support it.
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.