do you mean running program directly from CD .
this option is only possible when software itself has rescue/recovery option, that will allow to make bootable CD. if your antivirues does not have this option,then you will not able to make bootable cd and scan your harddisk for virus .
(software company generally does not allow this because in this way 1 cd can be used in many computers.even Norton ghost 9 does not have recovery option, so when OS doesnot load, you cannot restore your data or image file. for than it ask to buy seprate Symantec rescue CD)