CAll the Writers Guild, and find out how much a copy of their Journal
costs. It lists the "contact person" for each show. If that show isn't
listed, pick the story editor. A letter is your way in, but do NOT include a
synopsis. State that the script is finished, that you would like to submit it
(if not through an agent, then using a release form of their choice) for their
perusal. After that, it's up to them.

jms