Didn't pick up on your edit earlier, better to post a new entry (same thread though) next time.
Anyway, to answer your question:
Take a look at logger
, it was made to test the syslog log system.
You can specify facility-level pairs, add messages and tags and more (do take a look at the manpage).
2 examples from the manpage:
logger System rebooted
logger -p local0.notice -t HOSTIDM -f /dev/idmc
This command is also nice to use in scripts.