An analog clock that uses a jpeg image of a watch face can be downloaded as a zip file from click here. Since the dial is a jpeg (clock1.jpg) it can be modified in any graphics program to replace the digits with roman numerals.
I have also found another analog clock that can be modified to show roman numerals by replacing the 1 2 3 4 etc in the code with the required I II III IV etc. click here . Unfortunately this one is a little gimmicky as it follows the cursor and could become tiring after a short time. I did find some other analog clocks that were fixed on the screen but couldn't see any way of changing them to roman numerals.