You can define these parameters in the /etc/system file, which is read during the boot process. Each parameter can be identified by the name of the kernel module that it is in and a parameter name that identifies it. See Tuning a Solaris System for more information.
The names of the symbols, the modules that they reside in, and the default values can change between releases. Check the documentation for the version of the active SunOS release before making changes or applying values from previous releases.