Being the self-appointed consigliere of "antipolygraph.org"  :), I'll give you my opinion (I am a lawyer):

1) For reasons too lengthy to explain here (but that also make common sense), your fraud in signing a different name to the waiver or any other contract will not allow you to weasel out of what you signed.  The law looks disfavorably upon fraud and will be loathe to confer a benefit upon someone perpetrating it.

2) As far as a lawsuit, you first have to show what your damages are, otherwise a lawsuit will not succeed.  Assuming damages, one shows gross negligence by demonstrating that the defendant deviated in a major way from accepted standards of care and accepted professional practices.  It's a  little difficult in the polygraph context because it's such a pseudoscience and there's a wide range of latitude as to what are commonly accepted practices, and what would violate a polygraphic  standard of care.  Polygraphers have been known to be abusive, confrontational, threatening, et al., all within the range of what is "accepted."

However, such a lawsuit is possible under various legal theories, and indeed, you should refer to the  current lawsuits which are pending and which are covered on this web site.  Attorney Mark Zaid (zaidms@aol.com) is representing the plaintiffs in a class action suit and if you believe you have a cause of action, your best bet is to contact him.