> I followed all these steps and the package builds and installs nicely.
> I still have one problem though: when I deinstall the package, I get:
> 
> pkg_delete: unable to completely remove directory '/usr/pkg/share/pixmaps'
> pkg_delete: couldn't entirely delete package `amsn-0.96'
> 
> This is because the xine and pan packages also install files to the
> pixmaps directory.

In your PLIST on that @dirrm line put a @comment in front of it, like:

@comment @dirrm share/pixmaps

That is a quick fix. I see the current package doesn't appear to handle 
it, so this is no worse than before.