Oh, yes, you have to be really on top of your participants for this pose! Make sure you get everyone facing the same direction to start, and then be very clear about which leg should be in front. I tried all the cues, from "right foot" to "leg closest to me," and STILL would end up with someone - often several people! - with their back to me going into it. So as they set up the lunge, you have to really look out and see who is set up to start. Make eye contact with each person who has the wrong leg in front; I haven't done this with a huge class, but it works well with the smaller classes, gently explaining that it helps to get us all where we need to be.
The cues the program gives us are perfect, keep using them calmly and clearly, changing them a bit as you change to the other side. The only other cue I added to help people know where to put their attention was, "Allow the weight of the bottom hip to help deepen your stretch."
One class I made people laugh by saying there was something about this stretch that made me think of showgirls, and that got everyone to do a little flourish with their extended arm. :) Nothing like a laugh during the poses that make people self-conscious to make them loosen those muscles a little more, right?