I have been thinking about this subject, and I have changed my mind to vote "yes, you can get an IPC in an aircraft with only a WAAS GPS, with some help". Here's what I'd do (I am a CFII) for this pilot:
I have a handheld nav-com (Sporty's). The VOR is pretty crude, it shows only a digital presentation of the VOR radial. (I think newer versions are better than this). The PTS allows combining various elements. So at some point, I'd give the pilot the handheld, turn off his GPS, and have him demonstrate a VOR approach using just the handheld. If I was really mean, I'd turn off his primary EFIS, too, and require him to use his backup (assuming he had one). I believe this would satisfy a requirement from the "Emergency Procedures" element, as well as one of the "Non precision approach (VOR)" elements. If he was using his backup attitude instruments, it would also satisfy the partial panel requirements. Since I don't practice emergencies in actual IMC, this would have to be done under VFR.
Note to Dan:
"My answer is based on the Instrument Pilot PTS (FAA-S-8081-4E, chg 1&2), page 7. The "Aircraft and Equipment Req'd for the Practical Test" has the verbiage "or area navigation (RNAV) and one precision approach:" (and LPV is an option for the precision approach) included that addresses RNAV equipped aircraft."
I think you're mis-reading the PTS. I did the same thing the first time I read it. Preceding all this it says "two non precision approaches..." and then there is a long list, ending in ".....or area navigation (RNAV)". Then it begins the list of precision approaches. It really needs a semi colon after the (RNAV) to make the meaning clear.