Assuming that you are working on AEM ver >=6.4
1. Create a workflow model that you need to trigger along with Rollout. Workflow model will be stored at /var/workflow/models/
2. Define new rollout configuration (type cq:RolloutConfig) at /libs/msm/wcm/rolloutconfigs. You can simply copy/paste/edit any OOTB rollout configuration:
3. Add "workflow" node cq:LiveSyncAction. The node must include a property "target" type of String. Use a path to the workflow model created in step #1.
4. Finally, add your custom Rollout configuration to the LiveCopy page:
Afterward, rollout action will trigger the workflow.