Push my apk to /system/app

I can install an APK to /system/app with following steps.

1. Push APK to SD card.

   $ adb push SecureSetting.apk /sdcard/  
   

2. Enter the console and get the shell

   $ adb shell
   

3. Switch to superuser. If your device is not rooted, get it rooted first. (If you don't know how to do that, just Google.)

   $ su 
   

4. Remount the system partition with WRITE permission.

   $ mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system 
   

5. Cat your APK from /sdcard/ to /system/ , some guys get a fail with cp command due to cp is not supported. So use cat instead.

   $ cat /sdcard/SecureSetting.apk > /system/app/SecureSetting.apk 
   

6. Remout /system partition back to READ-ONLY, and exit

   $ mount -o remount,ro -t yaffs2 /dev/block/mtdblock3 /system
   $ exit
   

Then reboot your device, the APK should have been installed on /system/app.

Normally, the only way to get access to the "/system/" directory is to have a device rooted. I don't exactly know if that is required for the emulator though. That could be your issue.