I'll try that. I was just using the clicking that I do when riding. My trainer suggested I get my husband behind her with a whip but I feel like I ought to be able to do this on my own.
When you lunge her - give her verbal commands as you do it. Make each command with a different inflection. Slow waaalllkkk, short sharper command Trot! and sharper CANTER!
She will learn the voice command to match the action. Then carry it over to the lead. If you were to ever show her, she must trot on lead on command.
I don't think I'd have your husband behind her with a whip, no sense running her over the top of you - plus she should feel safe when you are leading her, but know that you are in charge. If necessary, tap her with a whip on the rear end, don't hit her.