setup AIX for Internet access

It's not fully clear from your question what do you want. If you want to use AIX box as Internet client, all what you need - have your network connected to Internet. Box should have IP address and it will not differs from any another computer.

Ifyou need to setup it as Server for Internet, you should connect it by any way to Internet and provide public (Internet) IP address either by assigning it directly or, for example, using NAT on firewall. In this case you should be carefull in number of services installed. The gold rule - stop all services you don't really use. And in this case you should talk with your network / security manager to make all required changes in network and/or firewall.

Good luck.