Changes gone after reboot? Not with chdev - this command changes attributes of 'devices' in the ODM database - pretty solid...
The chdev/route command is exactly what smit(ty) does - that's where I got it in the first place, except you first have to clean up with route -f or route delete, because if a route is already in place, then the chdev command above will complain about it or will just install a parallel default GW...
HTH,
p5wizard