A pivot slip you'd have to go 180 degrees with the skis while the body faces the same way.
I frequently do them with rotary input. You're just pointing the skis where you want them.
It's falling leaf. The basics are you're sliding downhill. Then you're going back and forth tips pointing up, tips pointing down.
How you accomplish that is up to you and what you're after. There are actually a lot of ways to do it. It's a simple form, with a lot of answers.
You can do it like Lfeet proposed in the OP. You can do it like fatoldman proposed, with rotary.
You can also get the opposite results just subtley varying what Liquid feet was doing. That is, you can get the tips to go uphill with weight forward, and the tails uphill or tips downhill with weight back. Usually involves a little more edge. That's weird, no? Two opposite results.
It's not so simple. Or it can be, but understanding all the variations is important for someone to teach one of them.
We really need some firm snow for people to experiment. Last weekend not so good usually.
I like to do them often another way. I like to push the feet forward - that gets the tips uphill, then slide back and pull the feet back and let the tips go downhill.
I think the pushing of the feet can be a good skill as it can come in handy near trees etc.
Whatever way it's done, side slipping and falling leaf is important.
People should be able to side slip down a firm snow blue until they're bored to death. (Then you do leaf)
It is amazing how many intermediates and advanced intermediates cannot.