From Forum Nokia Wiki

#include <apacmdln.h>
#include <eikdll.h>
#include <install.h>

CApaCommandLine* cmdLine;
 
cmdLine=CApaCommandLine::NewLC();
cmdLine->SetLibraryNameL(_L("z:\\system\\apps\\install\\xyz.app"));
 
cmdLine->SetDocumentNameL(_L("c:\\system\\install\\xyzApp.sis"));
 
cmdLine->SetCommandL(EApaCommandRun);
 
cmdLine->SetTailEndL(KUninstallCommandLineTail);
 
EikDll::StartAppL(*cmdLine);
 
CleanupStack::PopAndDestroy();