I think Ven. Devananda, the abbot of IIT, did his MA thesis on memory.
As for the process of how to remember the past lives… I think that is not the question but I’ll answer it.
In the Pa-Auk system, the yogi does both rūpa and nāma kammaṭṭhāna usually after jhāna but before paṭiccasamuppāda. Then they are very sharp in understanding material matter and mind-moments. This is a necessary step and also perhaps more important than “purely-perfected” jhāna itself. With that, one learns how to see mind moments through the tool of present-life-past, remembering each and every mind-moment (like remembering yesterday, or a month ago). This is different from the “impossible to see” mind-moments of the present.
It is like going into a video editor and seeing frame by frame for an event that took place in the past (of the present life). The yogi successfully goes day by day, or year by year, until his paṭisandhi moment. Many obviously can recall being a baby or even in the womb, as that is “easy stuff” compared to past lives. Some have told their parents about what happened during the time of being a baby and “weirded out” their parents for remembering it.
Well before this stage, the yogi has actually gone back to his paṭisandhi moment and discerned the 30 rūpa there, actually during the initial learning of the rūpa stage of meditation (before learning nāma).
The past life remembering:
The cuti-citta of the previous life is, of course, just one mind-moment before that paṭisandhi moment.
The cuti-citta of the previous life takes the previous life paṭisandhi and also the bhavaṅga object.
However, the maraṇa-javana of the previous life (near-death moment) takes the future paṭisandhi object (of this current life now).
Therefore, one can recognize the maraṇa-javana of the past life.
The bhavaṅga and paṭisandhi object of this present life may not really be known until the past life maraṇa-javana are known. Even though they are not known or “uncovered,” that object is “known” subconsciously. It will become recognized by the yogi when he sees it in the past life.
I can speculate that this familiarity helps in “linking” the memory of the lives together.
They also look at their body and discern the 5 khandhas. They try to get familiar with the previous life. They look to see if male or female. Then go further as well. It depends on the yogi. Eventually, all 5 khandhas need to become clear. After that they will do the 5th method. Later after they have discerned all lives, they will do the other methods.