Yes,
Turn wheel to 15
Toggle switch to bottom or HH:MM:SS
Turn board on, display should cycle and then stop with 3 zeros at the right most positions (M:SS).
Connect a button (maunal contact switch) to the input jack.
Press and HOLD the button, as display starts to count, keep holding...
Counting will stop and zeros will apear in the left 2 digits (hours). Let the button go.
Button presses will advance hours.
When the display has 1 hour less than what you want, press and hold the button. Hour will advance by one and then the button HOLD will cycle the selection to the minutes.
Again use the button to advance the minutes stoping one before where you would like it. Press and hold to advance to the next minute and then keep holding to get to the seconds.
When seconds show either release and use button presses to advance seconds or just keep holding and the display will cycle to show all 6 digits as they are set HH:MM:SS. With all digits showing a button push will start the clock. Practice till you get used to it.