I, too, have been using finely ground coffee from home, stirring it into the boiled water in the pot, and after steeping, pouring it through an MSR filter into cups. Works very well, tastes great, and, another advantage--I can bring my own favorite coffee from home, and it can be Fair Trade coffee. The disadvantage, as compared to a contained method like instant packets or pods, is that there are coffee grounds all over the inside of the pot and the MSR, even after emptying most of the grounds into a trash ziplock. Rinse water can be broadcast, but sometimes bear rules or other rules prevent this. No real disadvantage to the MSR retaining grounds day-to-day, though. And if my companions don't notice the residue in the pot before it's mixed with the next meal, then I get away with that...
In my mind the biggest advantages of this method are: I get the coffee I like, it can be Fair Trade, and I don't have all that packaging. Now if I could just learn to drink it black to eliminate the cream (curdles after 2 days)/creamer (ick!)/small can of evaporated milk (heavy)/powdered milk (yuck)problem!