Yes. Extract bubbles images from: Code: /opt/N9QTweak/BlackChat/round and from: Code: /opt/N9QTweak/BlackChat/usr/share/themes/blanco/meegotouch/images/messaging-ui Edit them to colors that you want and transfer them back. Reapply tweak...
/opt/N9QTweak/BlackChat/round
/opt/N9QTweak/BlackChat/usr/share/themes/blanco/meegotouch/images/messaging-ui