As mentioned above you probably don't need to change the rings. And if you do you just need to torque them properly, SRMs typically do not change calibration when you change rings, the spiders are pretty solid and aren't very dependent upon the chainrings for stiffness which can affect the torque readings on some other crank based PMs.
All that said, all it takes is an accurate weight plate in the 30 to 60 pound range and about ten minutes to perform the SRM calibration procedure. It's very easy to do at home. Just go buy a 20kg Olympic style weight plate (the larger center hole in the olympic plates slides right over smaller pedal designs making the test really quick) and have it accurately weighed at a UPS shipping center or other place with a routinely calibrated scale. That's the only special equipment needed.
SRMs support field calibration and even if chainring changes don't typically change the slope of the PM it's not hard to do a slope calibration at home and worth the effort to get the weight plate and learn how to perform the procedure.
-Dave