I found out from looking on the Hilton board that DCDT is a Diner's Club credit card promotion. It seems that you would have had to have registered by Feb 28 to get the benefit. There is some confusion on when the promotion actually ends however and some are wondering if it is still available. So you might still have a very small chance to get in on this. For this offer, from what I have read, you have to pay with your room with a Diner's Club card to get the Hilton points. (I don't have this card so don't know any more about it.) For American Express, OnePassLover wrote this:
_____________________________________________
I got an offer from AX and it appears there are different deadlines for the 4-stay bonus offer and triple points/double miles offer. Here is the exact wording from the letter:
"Activate before February 15, 2001, you are entitled to earn exclusive bonus with your next four qualifying stays charged to an American Express Card within 90 day of activation." (And I get a total of 60k for 4 stays).
"Double Dip on one stay between November 15,2000 and February 28, 2001, and earn triple points & double miles at any HHonors hotel worldwide for every subsequent Double Dip stay charged with an American Express Card during the same period."
_____________________________________________
So it is too late for this one too. But there is always next year.
I know that you can still sign up to become Hilton Gold in four stays by using code COE2 (or any of many others) but you won't get the 50,000 point bonus that everyone has been so excited over. Some have said that this bonus has been offered before in other years so we will just have to wait and see ...
You can get points by getting the Hilton Honors credit card (though I don't know if you can get this in Japan?) and by updating your profile online at the Hilton Honors website
www.hiltonhonors.com
You can update twice per quarter, 1000 points per update. There have been many writings about this on the Hilton board so I won't copy all of it here but good luck!
More Hilton info on their website, select Special Offers, then Earning Points and Miles ... and keep reading the Hilton boards on Flyertalk.com because surely any new deals will be posted the minute someone learns of them.