It looks like you have two options:
1. Edit/add your local.properties file and add two lines that point to your trust store .jks file:
javax.net.ssl.trustStore=<absolute path to your .jks file>
javax.net.ssl.trustStorePassword=<password for your .jks file>
2. Edit your JMS step and add some custom properties under 'Server Connection Info' -> 'Advanced':
Solace_JMS_SSL_TrustStore = <path to your .jks file>
Solace_JMS_SSL_TrustStorePassword = <password for your .jks file>
(Those properties are from this documentation)
Option 1 will probably interfere with other trust stores built into DevTest, so I would recommend option 2. Put your .jks file into your project under the Data/ directory, and enter '{{LISA_PROJ_ROOT}}/Data/<your .jks file>' for the 'Solace_JMS_SSL_TrustStore' property.