Sure, it can be done easily. As you say, all you need is a high contrast object to focus on and take a couple of shots. Better yet, any former RPG junkies (aka D&D nerds ), you probably still have one of those 20-sided dice, so roll a d6 with 1-3 being negative and 4-6 being positive, and the AFMA value from the d20.
Of course, there's doing an AFMA, but then there's doing it correctly...
Seriously, there's a reason Canon sort of discourages doing it in the manual, warning that it may prevent you from achieving proper focus. AF systems are neither perfectly precise nor perfectly accurate - multiple shots are required, the target must be appropriate, flat where the AF point is (the whole real one, not smaller-than-real little box in the VF), etc. I really recommend using FoCal or a commercial tool like LensAlign or SpyderLensCal, and take lots of shots.
I am not a big supporter of AFMA. It is different now because back in the day before automated systems like FoCal and now DotTune it was a little to out of control for me. Too many methods out there. There was the old ruler and hold your camera at a 45 degree angle? I'm not putting air in my tires, I'm working with expensive, high precision equipment. I prefer to have trained technicians that have the proper equipment working on my gear. They do multiple measurements. So if I think something is off as much of pain as it is I send it to Canon.
Very seldom does anyone bring up the operator manual. I have many times and am usually ignored. I'm not sure how many times I have read about people asking questions about other issues and the reply is "read the manual". I jokingly think "but ignore the page and warning about AFMA " Just saying.
Also without an automated system I always second guessed myself even using Lens Align. I'd set it one day, go back the next and got different results. I tried my 100L Macro and got different results at 8, 12 and 16 feet which supports the manual. For best results adjust at location.
One more thing. It is known that phase detect AF can be affected by different light sources. Incandescent and fluorescent will yield different results. Something else to consider.
I know people swear by it and I can see it's value with 3rd party lenses but there are times I think Canon put it in so they can save money on warranty returns. There is variation in every manufacturing and there are tolerances. If your manufacturing process is a little off one week and outside the specs the customers can fix it using AMFA. I know about that. 30+ years in manufacturing and trust me, you don't want to know what goes on.
Currently all my Canon lenses have zero AMFA on both bodies and I can produce tack sharp images on all of them. I don't bother if they are out a few ticks one way. Next day, distance and light changes and it will be out the other way. I really like DotTune as it gives me a good idea on my lenses performance. If out consistently more that 3 to 4 ticks it goes to Canon.
I can been contemplating getting Focal just to see what it is about.