There is no direct support for setting position via timecode. If the movie file has a timecode track, you can send the message 'timecode' to get the movie's timecode. There are a few other timecode-related messages that you can explore, check the jit.qt.movie reference for more info.
If you want to set the position with the timecode format, you would just need to do the math by hand.
I don't think the movie I am using has a timecode track. :(
Another alternative would be able to specify the frame number that
corresponds to a time value. To do that I would need frame rate and
total time of the movie. But after looking over jit.qt.movie documentation,
it looks like this information is not provided.
As Ben suggested, you can do the math yourself, and I think it's pretty straightforward. Use the 'getfps' message to jit.qt.movie find out the frame rate of its movie, use that number to convert hh:mm:ss:ff to a number of frames, then use the 'frame ' message to jump to the desired frame.