The way Bt works if you were to spinkle it around the mound it might kill the larvae, hence killing the mound. You might be able to put Bt into a syrginge and inject into the mound.(posted 9645 days ago)Please understand if you use a pesticide in a fashion that it is not labeled for then the EPA may come down on you.
Bt - Bacillus thuringiensis
Soil bacterium that produces pesticidal toxins. Once in the gut of an insect larva, the bacteria produce crystalline toxins that eventually cause the gut to become fatally paralysed.