You want have just org.chart to view subordinates for managers in MSS ?
OR You want perform the actions on org.chart like creation of positions / change /deletion etc ?
Here you have to understand few points.
in MSS Addon 1.0 from EHP5, there is a component called EMBEDED Orgchart which comes free in MSS. This looks like nakisa view. in this you can't perfrom create / change /delete etc. it's just a view of org structure for manager to view all his subordinates.
Nakisa is sap's 3rd party application. In Nakisa, orgchart applications are different, here managers can perform create / change /delete of positions or orgunits etc. It is not free of cost. its required license. And Nakisa is not required separate server. You can deploy all Nakisa components in your current EP portal itself.
Workforce viewer is the latest functionality which is part of HR Renewals of EHP6/7. May be this is also required some license. I am not sure. since it's having professional, managers etc roles.
Refer this sap help document Workforce Viewer - SAP Library