Work in practice? Meaning, how would in work in game?
I'm not really sure. In MMF, you can change the a pixel of color.
<img src="http://i61.photobucket.com/albums/h53/Sodisna/Untitled-2.png">
So, any colors in the entire sprite (sprite's animation too) that has those colors would get changed. That have that the match the RGB colors.
The first 3 blues are:
109, 213, 238
69, 151, 238
18, 77, 168
Any color pixels (with exact color values) within that sprite would get changed.
If there's a color pixel that has 109, 213, 239, it would get changed. Only the match color values would get changed.