We already did this unintentionally during our natural evolution. All we really got out of it were a group of humans who can run slightly faster on average, and a group of humans who can drink milk as adults without shitting themselves.
I imagine the timeframe to get any noticable results would be in the thousands of years, even with deliberate selection for specific genes.
My laymans assumption is that acupuncture likely has a counterirritant effect, which can make pain seem less pronounced.
Sort of like how punching yourself in the side of the head can provide relief for a migraine.