set the package publisher
# pkg set-publisher -G http://pkg.oracle.com/solaris/release solaris
list the packages to be installed
# pkg list -af 'pkg://solarisstudio/developer/developerstudio-125/*'
dryrun install because, you know, this is solaris and all.
# pkg install -nv developerstudio-125
do the install
# pkg install --accept developerstudio-125