You'll just need to tweak paths from /opt/local (SmartOS) to /usr/pkg (OSX).
The one caveat is that multiple repository support in pkgin is not great right now. It should be ok as long as your site-specific packages are separate from the rest, and have unique names etc. This is something we hope will be fixed during this year's GSOC.
http://www.perkin.org.uk/posts/creating-local-smartos-packag...
You'll just need to tweak paths from /opt/local (SmartOS) to /usr/pkg (OSX).
The one caveat is that multiple repository support in pkgin is not great right now. It should be ok as long as your site-specific packages are separate from the rest, and have unique names etc. This is something we hope will be fixed during this year's GSOC.