Yes! It absolutely is possible to experiance the between through the DMT flash!

...I'll get back to that

First, terence mckenna did give a prominent Tibetan lama DMT:

(I've always thought the Tibetan lama was Chögyam Trungpa Rinpoche, but I could be wrong.)

...mckenna says "lesser lights" which I feel may have been a mistake in nomenclature, though it's obvious what was meant.

Keep in mind, the lama said  so he was referring to The Chikhai Bardo, which is distinguished by the sight of the Primordial Clear Light or the "Clear Light of Reality"

I have felt that the DMT flash and The Chikhai Bardo were identical states since my first DMT experience...

Even when confronting difficult states or beings while navigating the various bardo states, it is recommended to focus your mind on the clear light:

The Bardo Thodol (Liberation Through Hearing During the Intermediate State; Tibetan book of the dead; etc... ) can double as a guide to navigating the DMT flash....

I think mckenna was correct when he said

however, with DMT, it's as if there is a "cosmic cord" connecting your conscious-being to the physical body from which it departed, so before you can leave the bardo (the between; the state after death but before reincarnation ) you are pulled back into the physical body from which you departed...

...so it is "as far as you can go, and still be able to return"

Believe me or not, I had been perusing these connections between the bardo thodol and the DMT flash long before I was aware of mckenna's comments on the matter...it was the flash itself, I knew I was in a state after death, but before reincarnation, or whatever comes next, I knew where I was and I knew I had been there before...

Below is a quick description of the first bardo, it's also an amazing link, which can also double as a guide to the DMT flash:

Any way, I have a rant on this topic on many threads through out this site, and would be happy to elaborate.

-eg