From T3 under the hundreds of hanging butterflies (you'll see what I mean), take the escalator down to the tram. The tram will drop you off at the D gates. Walk into the rotunda and go to the right to another tram which will take you to Terminal 1. When you get off that tram, you can have a TSA agent let you though a glass door (it's sterile to sterile so no worries). You can now either take yet another tram or walk to the any of the A, B, or C gates. SWA is all of C and some of B. Allow about 20-25 minutes if you're going to the A or B gates. I believe there is also a ground shuttle between terminals, but this way you won't have to go through security again if you start inside security at T3. Hope this helps.