Ghamidi Sahab has not prescribed any particular method in this regard, instead he has left the matter to scientific methodology. And of course whatever scientific method is selected by the state, it will be legally incorporated for Moon Sighting purposes.
I am reproducing an excerpt from his article on Moon Sighting:
…”The purpose of sighting the moon is to determine a lunar month. If thirty days are completed in a month, moon-sighting is not required since in this matter we are absolutely certain that whether the moon is sighted or not, the previous month has ended and a new month will now begin. With advancement of technology, we are now in a position to determine if a lunar month can be of twenty-nine days. We are now in a position to know with full certainty when the moon is born for this earth each month. Hence, there is nothing wrong if the lunar calendar is instituted on the basis of the moon’s birth with respect to Makkah, and if all religious festivals are celebrated in accordance with it. The purport of religion is ascertaining the lunar month. If it can be ascertained by sighting the moon, it was adopted in the past, and if now it can be determined through some other way, then no objection can be raised against it“…
Source: Sighting the Moon