The way things were worked out was more out of necessity than carefully planned, since I only had a few plants available to experiment upon; and I had already been using 1/4 strength 30:10:10 orchid fertilizers on all of the Nepenthes for several years.
I applied the coffee in the same manner as the fertilizer, by pouring it through the media -- over the plant leaves themselves -- until it visibly drained, as one would conventionally water any plant. Initially, I was somewhat concerned about algal growth, though I had never experienced a problem or damage to the sphagnum moss with the dilute fertilizer in the past; but I was worried about the possible effects of the added coffee.
There turned out to be no need for concern, and I immediately noticed a marked increased growth of the sphagnum within ten days of the coffee application -- and, visibly, more rapid growth of the plants themselves (notable because most of the highlanders, otherwise, develop very slowly).
I have only applied the coffee once and the most current recommendation is treatment every six months; provided that no harm comes to the plants, I will continue using it. The 30:10:10 has been applied biweekly throughout this time.
I will post photos of the other -- eighteen -- subjects down the line; whether I can "afford" to experiment on them remains to be seen. I honestly don't wish to kill my plants or attempt to replace them . . .
I am also awaiting a shipment of more -- expendable -- Nepenthes seeds to more formally experiment upon . . .