I tried adding the necessary files to a running ROM, but the system.img file is reset each time you restart the emulator. There was a temporary copy of the modified in-memory version in my account profile temp folder, but copying it just gave an unbootable image. In the end I found doing a ROM build on my Linux machine and extracting the system.img from the build, adding the files, and repackaging worked.

You need:

• system.img to modify (.\android-sdk-windows\platforms\android-10\images is one place to look)
• GoogleServicesFramework.apk and whatever Google apps you want (like Vendor.apk, etc).
  • Copy from your existing phone or check out Google Apps download section for CyanogenMod
• Linux (I used Ubuntu 11.04 64-bit)
• unyaffs - (I used the precompiled binary without issue)
• mkyaffs2image - (You also get it if you are building a ROM)

Steps

1. mkdir EXTRACTED
2. cd EXTRACTED
3. ~/unyaffs ~/system.img
4. Copy whatever you need into the extracted content
   • Example: cp ~/GoogleServicesFramework.apk ~/EXTRACTED/app/
5. mkyaffs2image EXTRACTED newsystem.img

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