Windows Live Messenger handles most of the colorize features itself. As long as you have the colorize-button available, you don't have to worry. All pictures doesn't get colorized. If a picture doesn't get colorized, and you want it to be, or the opposite, you can change the MetaData-flag for the image in your SkinInfo.xml file. Read more about that in the skinning-documentation.
If you have a color-resource in your SkinInfo.xml, and you want it to be colorizable, you have to use the <I>-tag. This is because it doesn't colorize the color by default, and it doesn't know how to without that tag. You can use these colors to make backgrounds or text-colors colorized. You could just use rcclr(<RESOURCEID>), so for example background:
code:
background: rcclr(490001);
And now, that background will get colorized.
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