How does Faber equip Montag to deal with Captain Beatty?
I assume that what you are talking about here is how Faber gives Montag the "bullet" to put in his ear.
What the two of them figure is that Faber will be able to guide Montag along. With the bullet, Faber will be able to hear what is being said to Montag and what Montag says. He will be able to speak to Montag and tell him what to say when Captain Beatty talks to him.
As it turns out, it doesn't help Montag much. At the firehouse, Beatty's words overwhelm Montag. At Montag's house, Beatty finds the bullet and takes it from Montag before Faber can really help Montag very much.