Welcome to the board!
I have not used the EPS for a long time, but I think you are(were) misguided by that article.
IIRC, the EPS can hold 16 multi-samples in each of its 8 layers - thus, 128 samples.
There MAY be a way of setting all 16 wavesamples in a layer to play in the same key range, but then you would only have the polyphony to play one key at a time... The EPS has a maximum of 20-note polyphony.
You COULD take the time to add waves to each other one at a time to make a giant composit of 128 waves, but this would take much time and - because of the limited resolution of the EPS - would result in a noisy mess.
"A thing may seem impossible...until it's done."