mkdir -p /usr/lib/rackspace-monitoring-agent/plugins/
cd /usr/lib/rackspace-monitoring-agent/plugins/
wget https://raw.githubusercontent.com/racker/rackspace-monitoring-agent-plugins-contrib/master/lsyncd-status.sh
chmod 755 lsyncd-status.sh

You can test the above script by calling it directly to see if it is working and reporting stats:

/usr/lib/rackspace-monitoring-agent/plugins/lsyncd-status.sh

Now, we need to create the alert itself.
[To get the token, you can use this]

curl -i -X POST \
-H 'X-Auth-Token: [AUTH_TOKEN]' \
-H 'Content-Type: application/json; charset=UTF-8' \
-H 'Accept: application/json' \
--data-binary \
'{"label": "Lsyncd", "type": "agent.plugin", "details": {"file": "lsyncd-status.sh","args": ["arg1","arg2"]}}' \
'https://monitoring.api.rackspacecloud.com/v1.0/[ACCOUNT_ID]/entities/[ENTITY_ID]/checks'

NOTE: ENTITY_ID is the Monitoring ID, NOT the server ID!!

Once the alert has been created, you can add the alarm manually via the Control Panel:

if (metric['lsyncd_status'] != 'running') {
return new AlarmStatus(CRITICAL, 'Lsyncd Service is NOT running.');
}
if (metric['lsyncd_status'] == 'running' && metric['percent_used_watches'] >= 80) {
return new AlarmStatus(WARNING, 'Lsyncd is running but the number of directories has reached 80% of notify watches.');
}
if (metric['lsyncd_status'] == 'running' && metric['percent_used_watches'] >= 95) {
return new AlarmStatus(CRITICAL, 'Lsyncd is running but the number of directories has reached 95% of notify watches.');
}
return new AlarmStatus(OK, 'Lsyncd Service is running.');

Make sure to test and save the alert.