Tailored RNP procedures are private procedures and not available for use by other carriers. That doesn't mean that in 5-6 years when SWA is comfortable with the technology they won't be giving SE AK serious consideration. The very same guys that developed the Alaska Airlines' RNP network are available for hire (Naverus). Coincidentally, Naverus has the contract with SWA for the implementation of RNP to include the design of hundreds of tailored approaches.
Naverus | RNP RNAV | High Performance Navigation