below the pole (the usual location for such a thing, but only if you're using a
digilines-enabled spawner). Sneak (usually "shift") still places concrete right
below the pole, so sneak + aux1 will place both.
As usual, if you're in survival mode, you must have distributors in your
inventory in order to place them, as with concrete and the pole and light
items; the mod will warn you if you have none.