Start with 2 elevators with 1 standing behind the other.  The elevator in front does not have backspot. 

Now have the flier in the tossing elevator (the back elevator) grab a thumb to thumb grip with the post elevator (elevator in front) in front of her. 

Flier in tossing elevator -  Stay as tight as possible. On count wait for the dip of your bases.  As they come up do not jump, but gently begin putting weight into the post in front of you by using the muscles in your shoulders. To continue the leapfrog lift your knees up to your chest, slightly lean forward, keep your chest up (but slightly forward), and tuck your legs to your chest on your way up and over . As you come over bring your legs down a little, keep your legs at shoulder width, and do not try to place your feet.  The bases will grab then when you come over.  As the bases grab your feet still resist through the posting flier's hands who is now behind you. As you bases come up to an elevator position shrug through your shoulders, lift up with your chest, hollow out through your stomach,  lift your chin up, and finish with a Hi-V.

Posting flier- Grab a thumb to thumb grip with the flier in back of you,  and keep your elbows bent.  As she is thrown over, straighten your arms, and resist the flier as she is thrown over you. Follow her over and assist her to your front.  When the base catch the feet, continue to assist the flier and help her up in to the elevator.

Bases of tossing elevator - On count dip with your legs and watch one another for timing issues. Give the flier a little toss up and follow her as you both make your way around to the front. Make sure your arms are up at all times.  Now reach high for the corresponding flier's feet and absorb the momentum as she comes down. Now watch each other, stand up, and bring the flier's feet to your shoulders and end in an elevator grip.