I've only ever knit one thing with eyelash yarn in my life (see my gosling). The pattern was actually from the same author! I found the perfect heathered brown that will work for the body of my hedgehog... but I do not have a color that is quite appropriate for the face.
I have black for eyes, and I'm have some wool of the andes purple that could work for the snout, although I decided to try to make a rosy pink myself. What I needed the most was to find a brown that matches the fuzzy yarn that I found in a bin without a label.
I used 1T vinegar per 2 cups of water on the stovetop. I brought it to a light boil, and then added the dye.
Color #1: 1 mL concentrated Brown solution (Wilton's paste dissolved in water), and 0.5 mL of concentrated black solution (using Wilton's paste solution). Add the wool, and simmer until most of the color has been absorbed to the fiber.
Color#2: Same water as previous (very little color remaining), 1mL of each Black and Brown solution. I added the wool, and allowed it to simmer until the color became a deeper brown than the previous. The remaining dyebath had evidence of black dye.
Color #3: Same water that was left over from #2, plus 3 drops of red food coloring. I allowed the wool to simmer in the dyebath until it turned a deep rose color. (All color was not removed from the water, but I did not want the pink to become redder or brighter. I wanted a muted color.)
Wet these look like they'd go with the eyelash yarn that I selected for this project.