You can't do that out of the box.
This is an example from the Codeplex site:
relatedColumns: ["System_x0020_Image", "Lead_x0020_Sales_x0020_Rep"],
This displays the fields "System Image" and "Lease Sales Rep" from the Systems lookup list when the field "System" is changed. The value selected in the System field is looked up using the Title field in the Systems list to find the data.