starway6, it is my understanding that plain unadulterated salvia leaf can be used buccally for great effect... Salvinorin A is absorbed through saliva. Twig's method seemed novel in that:
1) he claimed it was not nearly as bitter as leaf and
2) it is a standardized dose

Personally, I am excite to try it (both because I am interested in novel experiences, and because I want to help support Twig's endeavors). I have only communed with salvia 4-5 times, so I am by no means an expert.

But to answer to question, DMT and salvinorin A are absorbable through sublingual uses, but the enhancers he uses seems to increase absorption, so most likely yes, capsaicin (one of his "secret" ingredient he made public ) would likely help absorb anything that is already sublingually absorbable. IT excites the mucous membrane an dilate it and also reduce pain supposedly.
SO this is not specifically something that would only work with Salvinorin or other salvia divinorum diterpenes.

Cyclodextrins or "sugar-circles" are sometimes used for making 25nbomes active sub-lingually,
by drying 9 parts cyclodextrin and 1 parts nbome(Or maybe salvorin A) solution,
it's encapsulated with a sugar molecule, making it orally active.