I have a Custom Record that has a field called BOL Date. I need the BOL Date that was entered on the IR to populate on the Custom Record automatically. On the custom record i have a saved search view that is pulling the PO of that IR on the subtab. Is it even possible to create a workflow to populate the BOL Date field on the custom record from the IR?

You should be able to create a user event script on an IR that updates the custom record

@BarryMc workflows can only update values in the record that triggers the workflow. Workflow can get the update value from a joined record. As @nichol