Supposedly the way to book is to go to https://book.princess.com/affiliates/login.page
And type in Station, then next page asks for your name and Station cars number, then it will let you book cruise.
I just tried it and got an error. So I so don’t know if this means there are no cruises available now or some other error.
The cruises might be available only at specific times of year.
Does anyone have more info?