It is quite easy:
- Draw your stockings using different layers (eg. one for the lines and shades, and another for the RGB fill).
- The RGB fill layer will be placed under the lines and shade layer.
- Change your RGB fill into a symbol (F8).
- In the Properties tab, change its instance name to "rgbFill" or rgbFill2" (case is important).
- Et voilà!
You can read
How to make proper RGB mods that is more detailled.
You can also look at my
Bottoms - RGB Diamonds Stockings (legwearA sliders).fla and possibly use their outline and shade layer if you want.
These stockings have extra code so their colour is modified by the
Legwear RGB sliders, and they are draw on the
Body template, so they can be used either in Vanilla and the Loader, and not collide with other
Bottoms mods.
Good luck.