Yeah, we all go and put a script on /etc/rc2.d or /etc/rc3.d
But to be clean on Solaris 8, 9 and 10 you can add your static routes at /etc/gateways like this:
net 100.100.100.0 gateway 192.1.243.1 metric 1
for Solaris 10 11/06, we can use the “-p” parameter
/usr/sbin/route -p add 175.168.0.0 192.168.2.1
these routes are stored in /etc/inet/static_routes
have fun