After quite a few weeks of working on this, I've finally got it cracked. To use internet from NUS for whatever reason there maybe, you first have to log in to NUS via Cisco's VPN client. Now this does sound a bit circular, because to access NUS from outside, you would need a valid internet connection to establish a VPN connection to begin with. But however if you happen to be at a place that doesn't charge you for traffic to NUS, but does for everything else, then this is a solution for you.
1. Connect to NUS VPN using the Outside NUS profile on CISCO VPN Client.
2. Set your browser http proxy (and every other proxy) to:
Host: proxy.nus.edu.sg Port: 8080 or proxy.nus.edu.sg:8080
3. If the program of your choice doesn't support proxies (most do), then use a program such as Proxifier
Enjoy your free internet =) Theoretically, the traffic should be encrypted, because if I'm not mistaken, it enjoys the same encapsulation as the rest of the traffic that passes through the VPN tunnel.