How to pronounce “clocking”(verb) in English

Granada House rules stipulated a 40 hour work week, so Wallace got up at 4:30 in the morning to take the Green Lineand worked until 2:00 PM, walking a vast disk packaging plant in Lechmere, clocking in his whereabouts every 10 minutes and twirling his baton, or so he later said.Actually I don't think David ever did this, but it's in the letters he wrote.