Why don't we start with an easier lab-grown animal product than something we ingest?
How about lab-grown fur coats (EDIT from evilduck's comment: or lab-grown leather for clothing, furniture, shoes, etc)? Who wouldn't want to wear a "mink" coat created with no animal pain?
Develop the technology on something we don't have to eat, along with the associated health risks and sensitivity of our palates, but still useful. Then transfer the technology to the harder areas.
I wrote about in-vitro fur before -- http://joshuaspodek.com/vegetarian-entrepreneurs-test. I'd love to see it but haven't heard of anyone working on it. Is anyone doing it?
Another application easier than in-vitro meat for humans -- in-vitro meat pet food.