I played with a couple of them. Cut back to a bud or to a node point, just like spruce and fir, as any twig without a bud becomes a dead twig. Needle size doesn't seem to reduce, so it pretty much needs to be a big bonsai. Branches remain flexible for a very long time. One is now in my landscape, the other is compost.
If you see one for a reasonable price, have a go at it. Branches are largely autonomous, so what you do to one has very little effect on others, IOW you can test pruning strategies/techniques on individual branches. wiring effects, and etc., to figure it out for yourself. With spruce, some people suggest pinching the newly emergent foliage as soon as the bud cap pops off. My trying this with Concolor gave the same response = just basically shortening the shoot. I didn't notice any second flushing per se. With spruce the strongest back budding response comes with pruning the new shoot back to a bud after the new foliage is hardened. In August seemed best. Earlier weakens the tree. Later seemed to produce less back budding.
All in all, it seems to me that management of Concolor is much the same as for spruce, IMHO. There is a number of other fir and spruce, though, that have much shorter needles and are, therefore, more conducive to making moderate size bonsai - subalpine fir, bird's nest spruce, oriental spruce for examples. If you are particularly rapt of the blue color, picea pungens. Blue spruce seems to make nice gnarly bark at the earliest age.