It would be no different than planting a cutting you rooted in water. Make sure the soil you are planting too is thoroughly damp as dry spots will cause burned roots. Hold the plant at soil level in your pot and gently add soil around and through the roots trying not to break them up. After the soil is added, water thoroughly to pack the soil against the roots.
Are you using a non-soil planting medium in the hydroponic system? Clay pellets, rock wool, pebbles...? Or are they just in water?