there you go: the external + helpfile (mac only at the moment)
I hope it works fine for you.
- the markers should be in an .asd file, so you should press the 'save default clip' button after setting the markers
- you need to know the location of that file. Currently I don't think it's possible to retrieve the path of a clip with API commands (if there is, please let me know!) so you need to know it yourself, or drop the file also in the device where you use this external