how to add log_archive_duplex_dest without shutdown

Hi,
I have the following setting in my init file right now and the database is up and running:
##### For archiving if ARCHIVELOG is on ########
LOG_ARCHIVE_DEST =O:\Ora_archivelog\Orant\database
LOG_ARCHIVE_FORMAT =QIS1%S.arc
LOG_ARCHIVE_START=TRUE
text_enable=TRUE
##########

I need to add a second destination for the archive logs without brining the database down. I am looking for the statements. Please reply.
Thanks,
Ramesh

log_archive_max_processes = 1
log_archive_start = true
LOG_ARCHIVE_MIN_SUCCEED_DEST = 1
log_archive_dest_1 = "location=DISK$ORADATA:[ORACLE_UTF8.DB_ANIMO.ADMIN.ARCH] MANDATORY"
log_archive_format = arch_%t_%s.arc
log_archive_dest_state_1 = enable


alter system set log_archive_dest_2 = "location=DISK$ORADATA:[ORACLE_UTF8.DB_ANIMO.ADMIN.ARCH1] OPTIONAL"
alter system set log_archive_dest_state_2 = enable;

Thanks for the quick reply. It worked.
Ramesh