Sorry I don't have the answer, but ...
You may not want to. I haven't talked to as many people upset about Trulia's estimate as Zillow's but the estimates can be a conversation starter for an experienced agent. Serious home buyers are quite well informed. A person spending their time looking and really wanting to buy a home isn't going to depend upon a computer generated estimate. If they ask your agent why the computer estimate is lower/higher your agent has a great opportunity to tell them about your home ( ... and more).
The biggest problem is out of area extended family members who are influencing the decision. They see the machine estimate and don't have real information to judge it by.
The most annoying problem is the sometimes seen self-annointed expert who walks into an open home and proclaims this house won't sell. The "machine" estimate is $100,000 less. It's about as much fun as a loud drunk.
Use an experienced top agent. They aren't afraid of machine estimates.
The out of area extended family issue can often best be handled by someone who speaks the language of the out of area family. It isn't unusual for Asian buyers to have strong influence from non-english speaking family members.
Top 3 agent nationwide at Keller Williams
Over 20 years experience