In this time while as a living being, it's possible but hard.
But after die and before the next rebirth, we are in a "pure" state that's easier to attain liberation, but most people miss this opportunity and fall into the rebirth.
Nowadays who would spend time to practice and prepare?
Transformation takes very long time and effort.

It's not about memory but the attachment

purify oneself everyday for a very long period of time then one day will reach liberation.

When you have rainbow body, then it's good enough, no need even to enter the bardo state, haha...
some people reach rainbow body state by just chanting om mani pehmeh hom whole life, dunno true or not.