Yoko-tomoe-nage is usually done from a kenka-yotsu situation. It's much harder to turn into yoko-tomoe if there's an ai-yotsu situation. Usually tori would do a kouch-gari on uke's far leg to create some space for tori to rotate into the technique.

But it's possible to do this technique without creating that space. It requires an "over-rotation" by tori. So, instead of aiming for the front of uke's far foot, aim for the back of the far foot.

The rest of the throw is the same.