There are several ways you can connect to the SP. Sorry to lead you back to IBM again, but here is a link to IBM documentation which lists the possible ways how to connect/configure the SP and how to perform these steps:
Appendix B: Supporting information for setting up consoles
Here is a description how to connect serial to the ASMI/SP:
Accessing the ASMI using an ASCII terminal
So far I usually used a web browser to connect to the ASMI. The ASMI is the configuration interface for the SP:
Managing the ASMI
Controlling the system power using the ASMI
There is of course an option where to view/set the network configuration of your Managed System (the system that hosts all your LPARs).
I mixed up information for p6 and POWER7 systems when gathering the information. Usually the same is available for all of the p/POWER type of systems. There could be different menus/options. Though you get a start where to look at.