I've done this in a Husky. We used colored powder, which can be purchased online or made easily enough with food coloring, corn starch, and some time in the oven to dry it out. From there it's no different than an ash dispersal, ironically.
If you search VAF for ash dispersals there are some great engineering solutions to accomplish the drop itself. Just brief, brief, and rebrief yourself to expect and resist the urge to look back and admire the color cloud. Eyes ahead and keep an appropriate airspeed.