Excel 2003

I have a co-worker who enters time on a spreadsheet. She would like to have
the time cells fomatted so when she enters 1456 it appears in the cell as
14:56. This doesn't work when I format, cell, time, 13:30. I've looked at
format, cell, special (which would be a logical place to put something like
this), to no avail.

TIA
CaroleO