Splunk will support you on Splunk issues if you're running on Veritas Cluster Server, but can't support you on Veritas issues as that's really your responsibility. That said, here is one way in which you can set up Splunk under Veritas.
Put each Splunk instance into a Veritas service consisting of and depending on:
Each instance is normally expected to run on a single physical cluster node. But to allow any instance to run on any node, you should also set configuration to ensure no conflicts by using different values for the following for each instance:
Forwarders should forward to the Virtual cluster address of each instance, using the corresponding input port numbers for each instance.
Search heads should query against the Virtual cluster addresses of each instance using the corresponding Splunkd port number numbers for each instance.