My understanding of mescaline is that if you are capable, it would certainly be worthwhile to consider some form of mescaline extraction.
The bitter truth (hmmm) is that mescaline bearing cacti are highly evolved plants that deliver a very clear, ancient message when you attempt to eat any of them... it's not spoken though, more felt - my interpretation woud be I'm not food. You will need to prove your worth before I give you anything, ape-thing.. That is, it tastes awful. You might be tempted to make some sort of paste or concoction, sweeten with sugar, whatever, but the problem is that the taste of the cactus is so pervasive, you will just end up making larger and larger volumes of only marginally more palatable cactusflesh.
So my recommendation is chop the cactus finely (after doing your best to de-spine it), add a tablespoon of citrus juice, citric acid, ascorbic acid, or vinegar (any time) to ensure favorable condtions to extract he mescaline.
Thankfully, mescaline and its family members are soluble in water in acidic media, and are stable enough that gentle boiling will not harm them. So it is not very hard to make a sort of cacttus soup, heated but not brought to boil, stirred every so often, until you decide that it's had enough, filter the liquid through cheesecloth (you could attempt a 2nd extraction too by adding the cooked goopy flesh to more fresh water with acid & repeating the process. May improve yields?)
Anyway, after filtering, you can gently boil the liquid down to a drinkable volume. You can add sugar or whatever but I don't know what good that;d do. You want to have a small volume of tea, because it tastes so awful it shouldn't be savored, rather taken like a shot of really bad vodka, with a chaser soon after to rinse your mouth. It's much better than trying to eat whole cactusflesh, according to most people who have done both.