Boot OSX but ingore errors.

Hello,
I am trying to fix a friends mac that is running OSX 10.5 I found that the reason it deos not want to get to the log in screen because its finding an I/O error on disk0s02. is there anyway i can fix that or have it to bypass any error and then i can reinstall once i get to finder.
Thank you.
Answer #1
You can boot from In Mac OS X, how can I boot from a CD or DVD and/or ignore my startup disk?
Normally, to set an alternate startup volume, such as a bootable CD or DVD, you should use the Startup Disk system preference. However, if your regular boot disk is damaged or if you can't set the CD or DVD as a startup device from the system preference, try one of the following options:
* Restart your computer and immediately press the Option key. Icons for all available startup volumes will appear. Click the one you want to boot from, and then click the right arrow button to complete the startup process.
* Restart your computer and immediately press Command-Option-Shift-Delete. You must press all the keys at once. The computer will start to boot from the CD or DVD drive. If there isn't a bootable disc inside the drive when you begin the reboot, the computer will attempt to boot from another partition or drive.
* Restart your computer and immediately press the c key. The computer will look for a bootable CD or DVD and, if it finds one, will use it as its startup device.

Try this to boot into the CD so you can reinstall.
As for fixing the problem i dont have a clue never have had this happen. Also you can take it to apple and ask them.
http://forums.macrumors.com/showthread.php?t=296908
Mad Jew
It's quite a general error that means OSX is having trouble reading and writing to the drive. Open Disk Utility and try repairing the external drive. If that doesn't help, then see if you can get your hands on a different cable or enclosure to test your current ones. Also, would reformatting the drive be an option if it comes to that?
Answer #2
i cant even boot into the os to get to any were i try to hold the commands so it will reconize the cd and boot from there. I know the cd is working becuase i just upgraded my mac to snow leapord with it. But i cant seem to have the other computer boot from the cd. But that computer will boot into a linux live cd so i know that drive is working.