Earlier this year, Lenovo made a small change on their T400 and related platforms.   The Ctrl-P option disappeared when attempting to access the MEBx (Management Engine BIOS Extension screens for Intel Active Management Technology).   If you browse through the Lenovo BIOS update posting, there is a brief mention of this change.

The main reason was to improve boot times.   The difference is a few seconds.   All of the Intel AMT functionality is still present.

To access the MEBx screen, press F12 during the POST process to access the Boot Menu.

The option "Enter ME Configuration Screens" will access the MEBx.

The option "Initiate a Remote Connection" is for the Client Initiated Remote Access (CIRA), more commonly referred to as "Fast Call for Help" - the ability for Intel AMT to make a call home for assistance.