"Above he wandered with the Creator of Things, below he befriended whoever could put life and death outside themselves, free of any end or beginning. He opened himself broadly to the vastness at the root of things, abandoning himself to it, even to the very depths." (Zhuangzi, 33; Ziporyn)
Despite this author's clear bias toward Confucianism, he had true insight into the heart of Zhuangzi's mysticism. It's really quite simple: Identify yourself so completely with the inexplicable that you lose yourself there. Putting life and death outside oneself is to identify with that which neither lives nor dies.
The one thing that cannot go on this journey is the self-identity. This is not because it is wrong, but because it is the psychological antithesis of vastness, where no discrimination between things can abide. Though there might be true comfort in snuggling oneself into the bosom of God, this is not identification with Dao. Dao does not snuggle. Dao does not come forth to meet the yearnings of the human heart; Dao is inhumane. For this reason, to identify with Dao is to have put life and death, existence, outside oneself. Dao is no guarantor of identity, either in life or in eternity.
The vastness at the root of things is Dao. It is so utterly beyond the power of mind to conceive that it is ludicrous to believe we can assign it any title at all. Yet it is ever present. We sense it everywhere beyond things. And we sense it everywhere in the things themselves. For there is nothing that is not utter mystery, however much we might know about it. And it is ever present in our tenuous experience of being in the world.
To simply open yourself to this so completely as to lose yourself there, Zhuangzi suggests, is to be free to wander without fear of any loss.
Zhuangzi suggests no explicit method by which to realize this state of mind. There are allusions to meditative trances, but no explicit recommendations which would lead one to believe that he himself sat in meditation. Those who do, tend to be rather emphatic about its necessity. Find your own way, he seems to say. And good luck!
You can check out Scott's writings on Zhuangzi here.