One is enlightened in a Taoist sense when one can grasp Te, and through it Wu Wei, leading to harmony with the Tao. How to know when you're enlightened is a bit of a trick question, because when you are enlightened, the question won't be important anymore. Thomas Merton described it quite nicely in his paraphrasing of Chuang Tzu:

THE TRUE MAN

What is meant by a "true man"?
The true men of old were not afraid
When they stood alone in their views.
No great exploits. No plans.
If they failed, no sorrow.
No self-congratulations n success.
They scaled cliffs, never dizzy.
Plunged in water, never wet.
Walked through fire and were not burnt.
Thus their knowledge reached all the way
To Tao.

The true men of old
Slept without dreams,
Woke without worries.
Their food was plain.
They breathed deep.
True men breathe from their heels.
Others breathe with their gullets,
Half-strangled. In dispute
They heave up arguments
Like vomit.

Where the fountains of passion
Lie deep
The heavenly springs
Are soon dry.

The true men of old
Knew no lust for life,
No dread of death.
Their entrance was without gladness,
Their exit, yonder,
Without resistance.
Easy come, easy go.
They did not forget where from,
Nor ask where to,
Nor drive grimly forward
Fighting their way through life.
They took life as it came, gladly;
Took death as it came, without care;
And went away, yonder,
Yonder!

They had no mind to fight Tao.
They did not try, by their own contriving,
To help Tao along.
These are the ones we call true men.


No mention of loving yourself or life...