0. Get permission
1. Drag the mesh and the textures it uses to your own mod's /mesh/ and /textures/ folders
2. Change the meshname of the entity file to the filename (without the extension)
Or instead of #3, just copy the entity file of the ship over to your mod and make it buildable in the PlayerWhatever.entity file, if it doesnt use any custom abilities, in which case you'll have to drag those over too.