Chances are good that you have a 3" triangular brush attachment. And a white terry cloth that fits over the brush. drag/push that combo (with steam)over one well lighted leather panel slowly, making several passes. On the second pass you'll see the texture of the leather change with the heat. The white towel will blot/absorb the oil and dirt, leaving a clean surface. Immediately (by hand-no applicator) liberally apply your conditioner of choice.
Do this once a month on your own seats. Wonderful.