If you have a Mac that doesn't have an optical drive, or your optical drive has failed, or for whatever reason your OSX machine doesn't have an optical drive, you can access a CD / DVD read-only on another OSX or
windoze windows machine.
First setup the share.
On a Mac go to System Preferences > Sharing and select "DVD or CD Sharing".
For windows follow the instructions.
If your OSX machine is not a MacBook air, to access Remote Disc you need to run two commands in Terminal:
defaults write com.apple.NetworkBrowser EnableODiskBrowsing -bool true
defaults write com.apple.NetworkBrowser ODSSupported -bool true
To use Remote Disc
select it in the Finder.
If, on the machine sharing out the Disc, you have selected the "ask" you'll need to click "Ask to use...". While this is kind of good for security, though no username / password is required, its tedious because every time you click on the Remote Disc you have to ask, and the request has to be accepted
after you click on "Ask to use.." it goes off and asks for permission
when the permission is granted, you then have access.