Hello Frank,
Yes the cup is handy for cold starts or when the engine has stood a long time and oil has drained away from rings etc. A Lister in top condition and with the rack in the start (excess fuel) position should start fine as long as you can crank it over smartly. If it seems un willing, then fill the cup once with oil and push the plunger down. This drops the measured amount into the intake, and it drops into the cylinder as the valve opens. this raises compression for extra heat and seals any slight leaks round rings and valves.Don't be tempted to use more than one shot at a time.You can break rings and lands through hydraulic lock. A second shot is OK if you have cranked it over a few turns on compression and blown the surplus oil out the exhaust. A lighter grade of engine oil helps if an engine is heavy to crank at low temperatures. Good tough old motor, the ST. Best of luck with it. Combustor.