This feature is new in the Solaris Express 12/03 release.
The Solaris installation programs enable you to configure multiple interfaces during your installation. You can preconfigure these interfaces in the sysidcfg file for your system. Or, you can configure multiple interfaces during the installation.
For more information, see the sysidtool(1M) man page and the sysidcfg(4) man page. See also the Solaris 10 Installation Guide: Network-Based Installations.