AIX Toolbox (linux tools for AIX)

ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/

Maitenance Level

Checking maitenance level:
oslevel -r

To display packages that need to be updated to get up to particular ML:
oslevel -rl 5100-09
The "09" part is maintanace level (ML9 in the example)

You can download latest maitenance level from here:
http://www-912.ibm.com/eserver/support/fixes/fixcentral

"Howto" describing ML installation process:
http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/iphbm/iphbm_updateall_howto.htm

Description of different kinds of AIX updates:
http://www.ibm.com/developerworks/aix/library/au-dutta_work.html