Teamviewer, Logmein etc might be worth considering. They have a secure channel of communication with their respective servers and are available for connectivity via a web browser.
If you're not wishing the network admins to know though, beware that they might be using monitoring software on port 80. We use Watchguard Firewalls all the time and use WebBlocker to either block or monitor usage. most firewalls these days whether it be Watchguard, Sonic Walls have this capability. I'm not really a Cisco person but i guess with their level of usage they also have very good built in monitoring.