I didn't feel the included battlescape skin for the 'Warbird' looked very piratey, so I spent a little time in photoshop and made it more to my liking. I made changes to the basescape plane sprite (hopefully the palette is correct), and the pedia image.
If you want to make your own changes I've included a photoshop file I was using to edit the sprite, I'd recommend using MapView then TileView and lastly PckView for exporting and importing the whole gunship as a spritesheet. As far as setting up MapView to view Piratez craft,
see this thread.
To install simply unzip into the mods folder found here,
mind you these are replacers for existing art assets. Dioxine_XPiratez\user\
mods