Id just soak it for a couple of hours, filter and then evap the IPA (or evap onto the other leaves you want to use). Id do a second round of soaking on the herbs to make sure you got all of the DMT, and Id keep the spent leaves just in case, if for some reason you feel that the new leaves are weak or whatever, Id add some sodium carb to them and do yet another IPA soak.
Do you know how much DMT is there? Also if I may ask, why do you want to do this, whats wrong with your enhanced leaves as they are?