unlocking it should do the trick . . . if you know how to.
I am virtually certain Cingular is selling the T68 in CA; you should be able to call them up, sign up for coverage over the phone, and get them to send a T68 in the mail.
alternatively, you can find a vender online that will either: (1) sell you one with a Cingular sign-up (that's how I got my T39 even though Voicestream never carried the T39 at all); or (2) just sell you an unlocked T68 (though this will cost you more).