Does JMS Messaging module supports “Solace System” messaging system which is alterative to IBM Websphere MQ.
A quick google reveals : http://dev.solace.com/tech/jms-api/
So yes , Solace has a JMS provider that will allow you to use the JMS Messaging Modular Input.
Just download the Solace JMS provider jar files and put them in SPLUNK_HOME/etc/apps/jms_ta/bin/lib
Then setup your JMS stanza as per the required Solace JMS settings , looks like all info you need is here : http://dev.solace.com/get-started/jms-tutorials/publish-subscribe_jms/
If Solace is a JMS-compliant provider, the JMS Modular Input should work since it has been developed against the (generic) JMS interface spec.