The specs don’t have to be in the machine to do an alignment. They should be able to give you a print out of the current specs of your car after setting the runout. But you taking it and putting the shims in while not on the machine defeats the whole purpose, as they’ll have to do the runout again when you return to have the specs checked again. Your shims will effect camber and caster(even toe for that matter), so the alignment heads should be on it while adjusting. The hand held tools kinda work, but the car needs to be level for accurate caster reading and also turntables for caster/toe accuracy. A lot more room for error with them, if you’re not familiar with them and/or even doing alignments. I do alignments all the time on classic cars with a modern wireless machine. Just get out a chilton or motors manual for the specs and adjust. Just did a 65 Galaxie today, a 68 Coronet yesterday and a 51 Ford a few weeks back.
...And actually it is kinda like rocket science, if you’re off by 1/16 of an inch or even less, it could wear your new tires out in a few hundred miles. 😉