Thanks for responding.
I don't have any rootstock available, so it has to be air layering or cuttings. I have been watching videos on youtube and there is (as always) a lot of information, so it's difficult to assess the validity of it.
I found this video which I found rather curious. It is about cuttings. I don't speak portoguese, but with the sub-titles and what little I could understand I could make sense of it.
(1) The white powder he applies to the cutting is IBA rooting hormone.
(2) The reason a women's stocking is used to cover the bottom part of the cutting is to mantain humidity. He says that jaboticabas need a lot of water for rooting, and the stocking helps keep the cutting moist. On a funny note, I "think" he advises to take the stocking from your wife without her knowing, otherwise she might chew you out over taking it (or something like that

)
(3) You need to water this every 2-3 days. He says that jaboticabas need a lot of water for them to root.
Don't know if I missed anything else important.
https://youtu.be/4xNOCBJ0JKYCheck it out. Don't know if this is valid information or not, but it definitely is a very interesting take on this problem.