hey cinna, its my understanding that it is a very simple process, you just make an extraction or tincture as you would normally, say with a alcohol extraction and set amount of starting material, and just reduce/ evap. the alcohol till its almost gone, it will get kind of "gooy" and then mix w/ the vegtable glycerin. with such a little volume of alcohol in the overall solution you should have no "burn" from it. you could also use a crude salvinorin crystal extract if you know how to go about that. But you probably thought of this already. mind you i have never used vegtable glycerin though, so this is what we will call informed speculation.