Yes, you should be able to. (1) Make sure that the circuit breaker to that fixture is de-activated. (2) Remove the celiing fixture and unfasten the fixture from the two wires going into it from the junction box (usually held together by wire nuts). (3) Attach the wires coming from the junction box to the terminals of the new outlet you will be using. (4) secure the outlet to the junction box. (5) Re-activate the circuit breaker. If the former ceiling light was controlled by a switch, the new outlet will also be controlled by the same switch. DISCLAIMER: This instruction is for an ordinary run-of-the-mill ceiling fixture. If more than two wires are involved or the light is controlled from more than one switch, these instruction may not apply.