On the 9-3SS you can do both of those, no idea on the NG9-5, sorry. I don't even have the equipment at work to investigate if an NG9-5 came in, they don't use the Tech2 for programming and fault tracing, GM moved to a laptop based system called GDS that the new 9-5's use as well.
If you try LED lic. plate bulbs you could always order both and see if the 'regular' ones work, if they do you can return the 'error-cancelling' ones with the circuitry to trick the computers.
(Former) Saab Tech / Competition Prep