While preparing new version of zfsinstall, I've written sample version for minimal OpenSolaris installation over network. This script also includes disk partitioning. If complete installation is needed just replace pkg list with: entire SUNWcsd SUNWcs
Try it if you've problems with graphics on old laptops and you can't run GUI installer. You can find osinstaller script in MilaX mercurial repository on OpenSolaris.org.