No it is not currently possible to connect the cost to either a project activity or a Work Order.  However if the CRO Line is of type ‘Repair’ not ‘Disposition’ or ‘External’ or ‘Multi-Level’ and the Repair Shop Order is still in a state of ‘Planned’  then it is possible to connect the shop order to a Project Activity,   However other than via the shop order connection between the Project Activity and the CRO line there is no direct relationship, and the only way to support this would be to add a custom field on the CRO Repair Line for the Project Activity reference and then if required a custom command button to navigate to the activity. 

However iimmaterial of this connection to the project activity the costs and sales lines with still be reflected in the CRO

As the CRO repair was exeuted via a Shop Order it is not possible to assign the same cost to a Work Order.