Unblock App Store for Software Update Only

Behind our corporate firewall, we have all authentication of Apple ID's blocked. That means iTunes, the Mac App Store, iCloud settings, and most importantly Software Update now that Mountain Lion passes it through to the App Store. It's not actively blocked, but it isn't allowed by the default rules. We'd have to add the appropriate URL's to our web filter's whitelist. I'd like to avoid manually pushing software updates through Remote Desktop, if possible.

My searching hasn't given me much in the direction I'm headed. Can anyone give me some info or a link on how to allow us to pass Software Update through the App Store without enabling, for example, iTunes or App Store purchases? I can live with allowing the App Store, but I don't want to allow iTunes purchases like music or movies.

I'd belive that's the requirement we have to meet. Are there certain URL's that would allow IT to update the clients, but still block users from abusing our network via iTunes or other non-work related purposes?

Thanks!