Is it ethical to edit customer testimonials?

I work for a "therapist" of sorts and she's just asked me to edit client testimonials on our website to include more keywords in an attempt to improve our Google rankings for our websites. I am personally not comfortable doing any editing without running the changes by the people who wrote the testimonials in the first place. Some of these are over 10 years old, and it will be difficult to get in touch with the original authors, too. I need a way to refuse without putting my job in jeopardy. My initial thought is to have her make the edits, and post what she wants me to, but I still don't feel right about that. Any ideas? How can I explain to her that it's quite simply unethical to do this without risking my job? Or, I suppose I could just refuse and whatever happens happens. Input would be great! This is not the first time I've been asked to do something unethical by this employer. Unfortunately, our industry is not regulated at all, or I would report her - there's simply no one to report her to. I'm open to suggestions. Thanks.