We had to test a machine driven by a large motor supplied via diesel-generator. The motor-absorbed current when running was a bit less than the 600-A rating of the breaker but the starting current/time were too high/long to prevent a (correct) trip despite judicious adjustment of the 'settings'. These breakers are only designed for a small number of trips on high current so it wasn't something we could 'experiment' with for long.
My older, wiser, bolder, colleague suggested we reduce the set-speed of the engine, set the AVR (automatic voltage-regulator) low and on manual control, connect and close the circuit-breaker (operating it from an external supply) and start the engine, alternator and motor all together when the loads, voltages and currents would be much reduced. We could then bring the whole set up to full speed within the trip parameters.... It needed good coordination between us and was a bit scary initially, but it worked..... To be fair, we did ask the genset supplier for his thoughts which were initially unprintable but their engineer was curious, pliable, interested and eventually persuaded. He came to see the procedure but stood well to one side with his hands firmly in his pockets.
We used this procedure a few times until inverter-drives became more available making the process routine by comparison. We would not be able to do this with modern gensets.