http://unixarticles.com/content/2/158/en/how-to-create-lpar-on-ibm-pseries-servers.html
Any pSeries server or p5 server which supports LPAR requires a Hardware Management Console. The HMC is a separate PC running some code which enables configuration and management of LPARs. Thus, the "high level" answer to you question is as follows:
1) Access the relevant HMC
2) Create a LPAR definition
3) Allocate resources to the LPAR definition
4) Start the LPAR
5) Install AIX (if not already on disks attached to LPAR via adapters you selected in (3).
For detailed descriptions, start here:
http://publib.boulder.ibm.com/infocenter/eserver/v1r2s/en_US/index.htm
