become a captain at your airline, then ASAP a LCA, instructor, something that makes you different than the avg pilot. Rack up hours, stay in touch with anyone and everyone you know who goes to Southwest. Apply, update often.
Lotsa dudes in the applicant pool with TT much much higher than yours, but who knows what the future holds. Seems the only 'low time' guys that get on are military.
G'luck