you will need a check valve to do this or the pressure from the keg will push the beer straight out the pump, i used a pipe from the keg held on with a clip then a reducer to a 3/8 pipe which then goes into the check valve then another small length to the pump itself.
i have at times just released the pressure from the keg and connected straight to the pump when having a party as it will all get used that night, you can of course re-gas the keg if you dont use it all and it should still keep ok