I've open-sourced my ptex tools, repo - https://github.com/sopvop/ptex-tools
It currently includes two tools - one for reversing winding order in ptex
textures - helps with rendering alembic archives.
And another one for merging several ptex textures into one, helps when you
have several meshes with same shading but different textures.
Both tools can be used from command line or as python modules.