Well, it may seem obvious, but whenever I was interested in a certain style I would simply learn songs within that style. Such as looking up tablature on the net or if you have the patience, learning the song by ear.

There isnt necessarily a "rockabilly formula", but once you learn a handful of songs that exactly pinpoint the sound you like, you'll start seeing the patterns they use to create the unique sound and you just follow the same patterns. Once you learn enough songs, I think you would get very comfortable and the style would start to come naturally to you.

For instance, lets say I loved a certain riff that Megadeth performed. Well, I learned how to play the riff, and from then on I understood how to produce that sound if I ever wanted a song of mine to have that particular sound.