I don't think that you can email the failed attempts, these are the options for SMTP:
"Email notification of event - Specifies whether Cisco Secure ACS sends an e-mail notification for each event."
"Cisco Secure ACS uses the System Monitoring feature to detect the events to be logged."
It looks like the Failed attempts are not consider part of the events that "System Monitoring" checks.
It could as you mentioned "Generate event when an attempt is made to log in to a disabled account".