There is a guy i have talked to that also does this. When he prunes in July/August he sticks cuttings and buries some in the woodchips and mulch under the mother plant and by the next spring he has rooted cuttings. So these would be semi hardwood on his method. He said he has alot of success burying horizontally as well.
Blueberries seem to be nearly the same as canefruits… higher success of semi hardwood than hardwood…and easier than soft cuttings if you dont have a misting room/tent/area.
Personally i am going to root my blueberries in an opaque storage tote in the shade in sand and fine pines. I am rooting mulberries this way now.
Perhaps i will fail but it seems to me to be the least maintenance with the highest success rate and fairly easy to control the environment.