Were that this was allowable, there would certainly be a lot more Plats out there!
I don't believe you can "legally" do so. I believe you have to register yourself and stay yourself for it to be an eligable stay.
This would be a bit like the airlines allowing someone else to fly on your ticket and you still get airline miles.
Not to say you might be able to pull it off somehow (reservation in both names with your number being used, and they check-in first). But I don't think it technically would qualify.
Regardless, this question can only be answered by Starwood, as they are the final authority on their program. I suggest you contact them directly.
[This message has been edited by PremEx (edited 05-07-2002).]