While searching through the NCAA web site for an interpretation on this, I came across a "Ask the Expert" section, headed by one Dee Abrahamson. I sent her an email with this question, figuring that I probably wouldn't hear anything back. I was sure that the NCAA folks have better things to do with their time!
To my surprise, I received a reply this evening.
"You are absolutely correct...she can take as many signals as she wants BUT must take, or simulate taking, the last one once positioned on the pitcher's plate.
Hope you can pass that along to her.
Dee Abrahamson
Senior Associate Athletic Director/SWA
Northern Illinois University
Convocation Center Suite 200
NCAA Softball Secretary Rules Editor"
That works for me!