Take it to the plumber's merchant. Or just take the big threaded black plastic tube with you - it's the same thread (obviously) as the pump but a damned sight lighter. Explain exactly what you want to do and they'll have the fittings.
My fittings were about £9, IIRC.
You won't get fixed tonight, I'm afraid, so you'll have to return to the state you were before putting the pump in.
Vin