Seasoning a molcajete

A friend of mine got a Kitchenaid mixer for her birthday or whatever a while ago and I got very jelly. It was so big and beautiful and all the TV chefs use one, and it does so much! I've seen attachments you can get for it, to turn it into a meat grinder, a juicer or even a pasta extruder! A fucking ice cream maker!!!! So cool, I couldn't sleep for a week. Anyway, I finally brought myself round to the fact that I can't afford one, and even if I got one I would never use it often enough to stop feeling guilty about the price. So the low tech options for me age going to be the whisk, the mouli, and some kind of grinder.
I've never been able to use a proper mortar and pestle, there's no grip and everything flies out of the bowl and rolls around on the floor like an asshole. I saw some buzz around Thai granite mortar and pestles which has a slightly rougher texture than say, marble, and is meant to be a little easier to use (interesting thing about it here). But for the longest time I've had my eve on a Mexican molcajete. It's a wide shallow bowl on little legs made out of volcanic rock and is essential for making guacamole and salsas. You have to have real volcanic rock, apparently some cheap ones are made with a mix of cement which chips off and gets in to your food (here is a shop that sells the good stuff in London). And really the lava rock chips and gets in your food as well, which is why you have to prepare, or season it before using.
Step 1 is to soak it overnight, this gets rid of the surface grit
Step 2 is to get a handful of rice and grind it into a fine powder. It will start off looking like this, and four fricking hours and bright red and throbbing hand later it will look like this.
Gray powder that's a mix of rice and ground stone. This step will have smoothed the surface down a little and will have ground away the looser particles.
Step 3 is to grind some aromatics - I'm doing peppercorns, garlic cloves, cumin seeds and olive oil, and then you leave the mixture to sit for a few hours or overnight. The point is for the oil to penetrate into the remaining pores and seal them to create a smooth surface but with a coarse texture - does that make sense?
These babies last forever and get passed long from mother to daughter and the flavours of everything you grind in it are imparted into the stone so each successive salsa will be tastier than the last - but it pretty much obligates you to only grind similar things. We'll see when I finally decide to make a pile load of guacamole.