At this time I do not believe you can make Palo ressies before boarding the ship...it would be great, but I don't think you can.
Maybe if you had the REAS package.....can someone confirm who has done REAS pkg if you can book Palo ahead of time///
And another FYI....if you are on the official
DCL land/sea package your dining rotation WILL NOT be listed on your KTTW card at checkin at your WDW resort. You will have to wait until you get to your cabin and check your dining tickets that will be on your desk.