If your Mac doesn’t boot from an external volume or the drive doesn’t show up in Startup Manager even though it contains a bootable copy of OS X, it might need repair. The first order of business should be attempting to repair disk permissions in Disk Utility. If you plan to use the same hard drive for your bootable installer drive that you used to download the installer, you’ll need to copy the InstallESD.dmg disk image to your Mac’s internal drive.

Creating a Snow Leopard USB Boot Drive Using Disk Utility. Start by launching Disk Utility on the Mac. To do this, you can either search for the application in Spotlight or find it in the Applications folder. Locate the USB drive on the left-hand side of the window and click on its name, not its partition. Click the 'File' menu and choose 'Open Disk Image.' Locate the image file on your hard drive and double click it to mount the image. The image appears on your desktop along with any other connected media.

Here are some instructions from that will put the ISO onto the flash drive with a Mac. They won't make it bootable though. • Open a Terminal (under Utilities) • Run diskutil list and determine the device node assigned to your flash media (e.g., /dev/disk2) • Run diskutil unmountDisk /dev/disk N (replace N with the disk number from the last command; in the previous example, N would be 2) • Execute sudo dd if=/path/to/downloaded.iso of=/dev/disk N bs=1m (replace /path/to/downloaded.iso with the path where the image file is located; for example,./windows7.iso) • Run diskutil eject /dev/disk N, and remove your flash media when the command completes (this can take a few hours on slower drives) Now. After you read all that, on the Gizmodo page it says that if you want to make it bootable you should use a utility called Live USB helper they link to (which isn't there any more) and use a Mac mounting tool (which isn't there either!) to force the ISO to mount on the Mac so you can copy the files over. Windows media player 10 for windows 7. That article may prove useful, but probably not. I can find other copies of Live USB helper out there, but they are all Windows executables. One method that will work is to swap the hard drive out of the PC and into the Mac.