Currently K-PACS does not provide an interface for plugins but this is an interesting issue. What kind of interface would you propose? DLL, OCX or something else?
DLL, OCX, ActiveX no matter. Everything will be perfect to add new capabilities to K-PACS
Or, if it's easier for you, just a new button in the viewer gui with the ability to launch another program and a text file with the list of the dicom data loaded.