Thats an awesome idea to win attention!
Couple of ideas...
Direct approach:
Oprah has a message board. She may not read the posts over there - but pretty sure a good post over there will be noticed by people who can deliver the message to her.
http://www.oprah.com/community/mb_list_landing.jspa
There are 152 people on linkedin who say they work at HARPO.
http://www.linkedin.com/company/harpo-productions
Try and get in touch with them.
(And if you really want to go the extra mile - hire someone to find out the addresses of all these 152 people. And mail them a copy of the book with a letter.)
Indirect approach:
Make a list of the last 20 guests on the show. Search for them online. You may find someones email address or a twitter a/c. Get them to put you in touch with a producer of the show.