Need help reinstalling OSx from another Mac

I have 2 Macbook Pros. I zeroed out my HD on the older one, and need to reinstall OSx. I don't have the disc for the older one so i tried using the disc from the newer one to reinstall, but no dice. I know you can install the OS from another Mac, but i'm not sure how. I've done a few searches and all i can seem to find is booting from an external drive. I don't have firewire. I've got usb to usb and the install disc for the newest mac. Any help would be insanely appreciated!

Thanks!

(sorry if this is a re-post)

You could try and instal OSX on the zeroes one and then clone its startup disk onto an external HD disk using carbon Copy cloner.

If that external boot disk can boot up the other MacBook Pro then you can simply clone the setup from the external to the other mac.

If you dont have an external disk you can connect the two Pros up with a FireWire cable and put the target mac into Target Disk Mode - making it effectivelly into a disk drive

Mac OS X 10.6 Help: Transferring files between two computers using FireWire