From performanceU..

Get the big SuperSliders at Lowes, roughly 9x5.

Put a pillow or towel on a non-carpeted surface and kneel on it.

Put your elbows on the sliders and just go back and forth.

You might want to try it with one arm, but I'd advise against doing it with one leg.
That strengthens the psoas and ipsoas, and that might give you back trouble later.