Take a 1+ y/o well grown rosette with a thick root. Remove any stolons on it, but hopefully it hasn't produced offsets. Dig it up and removed any dead leaves and plant only the bottom inch of the stem, so the rosette is sticking up in the ground. Let grow a couple of weeks to establish, then cut the top of the rosette off and remove any remaining leaves, carefully pulling them off. You will be left with the " stump trunk" of the tree and the top of the trunk should sprout multiple new rosettes.
You will need to select the rosette carefully from those varieties that tend to have thick roots, smaller rosettes, and that tend to hold the rosettes closer to the stem and don't produce long stolons. Should work, but will likely need some experimentation to find the right variety and correct timing. This kind of surgery will likely put the plant back a bit, so it might last a couple of years. It might be necessary to cut the top of the "tree" off each year. It might also be necessary to remove the medium from around the root during the first or second year, before the surgery, to encourage upward growth of stem and root.
