VIP Check In are "awarded" one of three ways:
10 cruises on Carnival (all cruises count - even CTN)
Cat 11 or 12
CVC member (they no longer sell these packages any longer and
the outstanding memberships will expire 05-2012)
As for those who have "old" Carnival cruises that are not listed, you can have them added.
We had 8 added to our history. We faxed them embarkation pictures.
Also, remember that if you used a TA (which a lot of folks did back then) the TA may have some old records that can help you get the credit you have earned.