Open Disk Utility.app and restore the image to your USB Disk (the one you plan on using as the recovery disk, must be GUID HFS+j and at least 8GB). Make sure that you still have BaseSystem.dmg mounted. This is the 'payload' of the install, but it is not a bootable disk. If you open it, you will just see a folder named Packages. Look at the external disk and find InstallESD.dmg (it may be buried in a folder). Once the download finishes, force quit (must be force quit) the Installer. To make sure it doesn't auto restart you can open up a document with the old Save/Save As options and start writing in it (MS Office or Photoshop work). If it restarts you have to sit through the install process, and start over as it deletes the files. Here is the tricky part, you have to make sure that it does not restart the computer. The download is big, so it might take a while. It will verify your computer, and start the download. Use a GUID HFS+j formatted external disk (unfortunately, it requires a disk larger than 8GB, so you might have to use a different one than the one that will eventually become your recovery USB Disk).

Hdiutil attach '/Volumes/Recovery HD//BaseSystem.dmg'

Download macbook pro os disk