C#:
bool CanBuildCustomQuarry(Planner plan, BasePlayer builder, bool IsQuarryOrPumpjack)
// Called right before other built-in checks.
// Returning false will cancel the construction.
void OnCustomQuarryBuilded(MiningQuarry quarry, BasePlayer builder, bool IsQuarryOrPumpjack)
// Called right after player has built custom quarry or pumpjack.