You mention that you also want to automate startup. One way of achieving this would be to manually add an PASSWORDS_listener_name entry to listener.ora, specfiying a password in cleartext. Do not use the netmgr or the set_password command. I think this script should work (not got access to my 9iR2 ServiceGuard package control script at the moment):

Code:
$ORACLE_HOME/bin/lsnrctl << !
set current_listener listner_name
set password password
start 
!
Naturally you should make sure that your listener.ora file and your shell script are fully locked down at the OS level permissions wise and that they stay that way.