I've never tried Coke, but Coke does have caffeine so maybe that would work. I would only be concerned with the Sugar content, but I'm no expert. I don't think the caffeine works the same way as the salts. From what I've read, the salts open up the ducts, the caffeine stimulates the liver.
With the water and coffee enemas protocol I followed, this time I suffered from no doldrums or headaches afterward and by the afternoon after my flush I had a HUGE appetite, felt great, had energy, etc. I think the enemas are definitely worthwhile. After each of my other flushes I either had a headache or the blues, but this time I just felt wonderful!