해당 블로그에 원하던 답변이 있네요
http://devbible.tistory.com/142
//타 어플의 Activity 실행
ComponentName cn = new ComponentName("패키지경로","패키지경로.액티비티명");
//ex) ("com.android.music" ,"com.android.music.MusicBrowserActivity")
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
intent.setComponent(cn);
startActivity(intent);