In general, any special colors will have to be dyed by hand. I use Dharma Procion fiber reactive dye. Procion actually dyes the fiber, rather than laying a coat of color on the outside of it. This makes it color fast and safe, if your child decides that the clothes look yummy.
Procion fiber reactive dyes only dye natural fibers; therefore, if there are polyester threads in the garment, they won't be dyed. This actually leads to quite a nice looking trim effect when it happens.
Depending upon the color desired, I might have to order the color from Dharma, which will add time to the order completion date.