The powder they are talking about is probably food grade diatomaceous earth. It is supposed to be quite effective long term, as it causes their exoskeletons (shells) to deteriorate and eventually kills them. If you use this stuff (and my friend did, or rather we applied it together) you should wear a surgical mask because the powder is incredibly fine and flies around in the air and if you inhale enough it will gum up your lungs. It'll make you cough like made if you inhale some of it. You're not supposed to use too much of it, or get it wet, because if it gets wet if will be ineffective. From Amazon, we got a sort of applicator for it. It's an upside down type plastic jar type thig with a nozzle. You squeeze it to send the powder into nooks and crannies. We used this inside furniture (by turning the furniture upside down) and in the cracks in the baseboards, etc., and in electric plugs, etc.). It isn't poison, but it will really mess you up if you inhale too much of it.
Talcum powder won't help, the the diatomaceous earth is supposed to. We used it AFTER treating the furniture twice with the effective insecticide (also wear a mask -- it will also make you cough like mad and is toxic in large quantities.) Mess around with it a little outside so you can learn to control it. If you get a big blob on the floor and vacuum it up, the particles are so fine they will go right through your filters and come out the exhaust of the vacuum and go everywhere (yes, we learned this the hard way)
It's very big deal and takes a lot of time and is hard work. We had professional guidance, but we did the work ourselves and from all evidence, we were successful.