I imagine you've sussed it by now, but in case not:
Press the SHIFT button (lower right)
This changes the function of the radio pre-sets - two of them will now have illuminated displays above.
Press the one labelled SETUP
The main display should now show CLOCK - if it doesn't, press SETUP again until it does.
Now press the preset with an arrow above it.
The hour will flash - set this by carefully turning the volume control clockwise to advance or anticlockwise to move the hour back.
No press the preset with the arrow above it again.
The minute will flash - follow the same procedure.
When the time is set right, exit from the setup by pressing shift one or more times until the unit display is back to normal.
HTH
Rod, April 2008