Is it possible to plant lilacs if there are no seedlings, and there are only a few cuttings from the bush, and not young. As far as I know, the older the tree from which the stalk is taken, the less likely it will take root.
To the above I will add my "five cents". To help the cuttings get their roots, dip them in the growth stimulant solution for an hour. After, plant in a box with soil (sand, garden earth, humus) until the cuttings give root, maintain the soil moisture. When the thaw is finally over and the earth warms up, land in an open ground without forgetting to pour it under a plastic bottle. When leaflets appear, the need for a bottle will disappear.