To setup syslog on the XOS below a example - in my case I've used VR-mgmt (mgmt port) as the source, if you use VR-default you must change that commands.
To enable it use the command #enable syslog
That generates the following syslog message in EMC which you could use to trigger the alarm...
"02/15/2017 22:15:21 AAA[2241]: Login passed for user admin through telnet (172.25.25.202)"