We can get the same lengthy residual from boric acid or borate products that are labeled for roaches and ants, but these generally are applied in dry dust form. Applying a dry dust to exposed wood surfaces is not a good option. Some of the products, such as Boracide, are specifically labeled for application to "new" or existing construction for ants and roaches, but the directions for use tell us to apply it as a dry dust directly into voids or insect galleries (as in carpenter ants). If these wall voids are currently open it would be difficult to contain the dust to the wood studs using any kind of pressurized duster. You could sprinkle the dust along the base plate, but if that is all you are able to do you could achieve much better coverage once the walls are in place and a power duster is used through some small opening into the void. Then you would get the dust onto the studs and interior wall surfaces as well, greatly increasing the odds that the insects will be in contact with it. 

Similarly Borid Insecticide Dust is labeled for pre-treating new construction for roaches. It recommends applying the dust at 4 lbs per 1000 square feet, but to "base plates and plumbing voids", so you would not be able to successfully treat all of the studs nor the interior surfaces of the wall coverings. 

Those materials that you could easily spray over all of the exposed wood surfaces would have a relatively short lifespan. In contrast to the years of residual effectiveness of a dry dust of boric acid or diatomaceous earth, the spray-on "residual" insecticides may last a few months, and this may not be what the customer is thinking will happen. You can offer him this choice, but he may opt instead to have you "post" treat those wall voids with an inorganic dust product once the walls are in place, and this will give him the longest lasting material in those voids.