Packages are built for the SFE IPS repository with pkgbuild patched to use modern, hierarchical package names instead of the native SFE package names starting with "SFE". pkgbuild obtains the mapping from old to new names from the file packages.xml. That file and the spec and patches for pkgbuild can be found at http://hg.openindiana.org/projects/sfe/oi-sfe-tools/. The location of OI's mirror of the SFE specs repository is http://hg.openindiana.org/upstream/spec-files-extra/.
We are currently switching to a new build system. It will be described here once it is finalized.