Copy the following files from your MECM installation into the same folder as the MECM Plugin dll file

AdminUI.AppManFoundation.dll
AdminUI.DcmObjectWrapper.dll
AdminUI.WqlQueryEngine.dll
DcmObjectModel.dll
Microsoft.ConfigurationManagement.ApplicationManagement.dll
Microsoft.ConfigurationManagement.ApplicationManagement.MsiInstaller.dll
Microsoft.ConfigurationManagement.ManagementProvider.dll