Q. How do I get the bible for the show I'm speccing?
Depending on the show it'll be easy or tough.
Some shows don't let outsiders look at their bibles. Some shows don't actually have a bible. Some are happy to let you read it.
If you have an agent, have her ask the show.
Otherwise, call the show and ask for the writer's office and explain your situation. The writers' assistant can shoot you a PDF of the bible, if it's allowed.
You get the show's number by finding out what studio is producing it, calling their main switchboard, and asking for the show's production office. Or you find out the name of the production company (in the onscreen credits or on the IMDB) and call them (number's in the Hollywood Creative Directory).
Most of the information you need, though, isn't in the bible. A lot of stuff you don't need may be. Sometimes the bible represents an earlier conception of the show and no one's updated it. There's backstory in there that the writers haven't put into any episodes. The description of the characters may not get at the essence of those characters. Bibles are wishlists and prospectuses, not blueprints. Only carefully reading the scripts and watching the episodes will tell you what you need to know. (I discuss how to get scripts and how to watch episodes at some length in Crafty TV Writing