I too built and used that jig when I decided my NP was just a hair off. I talked to TeleVue and they encouraged me to try. The hardest part really was breaking free the 3 screws holding the lens cell. 2 were not too challenging but the third was a several day head scratcher and worry until it finally cracked free before the head was to damaged to engage the Allen wrench. I replace the 3 with stainless steel and used no loctite or epoxy and has held fine for the last 9 years.
I did have to wait for a good night of stable seeing to nudge the collimation in using Polaris but it’s very satisfying to know I can do it at will. I found the jig to be an aid but not absolutely necessary as light taps with a small block of wood at the right place also works.