the answers are in the answer and article
1. whatever username/password you want - the only think you need to do on splunk is enable inputs OR use a forwarder to monitor a syslog file system
2. there is no script, you need to enable syslog on IBM SVC and point the syslog stream to wherever you want
3. there is no addon i am aware of, however, you can create on and share with the community
Thanks @adonio ,
It seems you are trying to say to enable inputs in splunk on port like 514(UDP) to receive syslog messages. But It will not send all events like performance related data and To get that it is written in link to write script which will fetch data using command like lsmdiskgrp. So I am trying to use second way to fetch data in splunk using script (not using syslog stream) for that I need clarification.