To build Abyss please refer to the documentation on building an extension:
Note that Komodo skins need to be built using the --unjarred flag, ie.
koext build --unjarred
Once you have built and installed your own version of Abyss you can activate it under Preferences > Appearance > Skin.
Note that if you were already using the version of Abyss provided with Komodo you will need to switch back and forth between another skin in order to apply your own version of Abyss.