1. Open the image
2. Duplicate the layer
3. Set opacity of the second layer to 40%
4. Go to Image>Adjustments and play with the setting until you find a color you like.
5. Use the eraser to get the parts back you want to stay the original color.
This is the way i used, there could be something more efficient, but this is the only thing i could think of.
can't change the kit parts because their black and it's near impossiible to do that, onl really works on bright colours. The way I do it will take a while to write out, so instead, just download my psd file here...