Don't overlook the timing difference: the triple step chasse is timed 1a2 (like Samba).
Sort of like Samba, except that in most swing music, the "a" count is 1/3 of a beat, not 1/4. This is called Triplet or Swing Feel. When the music is played this way, there is no debating how it splits: It is always 2/3, 1/3.
For the music that is played "straight" (as opposed to swung), one can make a decision between splitting the beat in half, like Cha Cha, or into 3/4, 1/4, like Samba. Not all EC Swing dancers prefer the 3/4 feel. And although 3/4 is the official split for Jive, it's questionable whether that's really what's done in practical application. The faster the music, the more even the subdivision -- Jazz musicians will tell you the same thing. Jive is extremely fast, so dancing at a true 3/4, 1/4 subdivision is more a theory than a reality.
I've had this discussion here a few times before, and I hope not to start yet another nitpicky debate about the intricacies of beat subdivision (And if one starts, I'd prefer to split it off onto another thread). What I really want to point out is that the 1/4 beat interpretation of the second step of the triple is not especially necessary to capture the style of swing.
In other words, what I'm saying in my roundabout and typically long-winded fashion, is that I suggest Carol focus more on the movement than the timing. Or at least, not get bogged down by microscopic details of the timing.
As to what in the movement, I think the footwork, knees, and even possibly introductory hip action (depending on ability) are good areas of focus to help improve the feeling of the triple step, and in particular, help set the Swing triple apart from the Cha Cha. I'll elaborate if requested, but this message is long enough. :)
Regards,
Jonathan