If it is possible, do we need to write any plugins?
I wanted to know if there is any use case around TIBCO BE or EMS integration with WSO2-BAM.
There are several ways if you want to publish data to WSO2 BAM.
You can write a Data Agent which resides in your preferred other-vendor-product which pushes data to BAM. Refer http://docs.wso2.org/wiki/display/BAM230/Data+Publisher
Publish data via Thrift to BAM. Here the preferred other-vendor-product is language independent as no need to use Java.
Publish data to BAM via REST API. Example is given in http://docs.wso2.org/wiki/display/BAM230/Sending+Events+through+the+REST+API