Once you admit that you kind of need Enya to provide the air movement, I believe the rest can be achieved through creative use of EQ and reverb.
One trick is to take the vocal track, send it to a reverb bus and put an envelope on the send so that only the sustained vowel passages are reverbed heavily. Then put a high-pass on the input to the reverb so that only the higher freq band is reverbed.
Then experiment with variations thereof.
Also, there's some harmony AHHH vocals in the background which I've reproduced in the past by heavy use of pitch correction, followed by similar effect chain as above.
Sorry I don't have samples to share... and I could be way off base, but this is what I would try.