Only for Macs that ship w/o an internal DVD can you so if you use to be able and now cannot.... if you don't have an internal superdrive.
Mac 101: Using Windows on your Mac via Boot Camp
Boot Camp 4.0, OS X Lion: Frequently asked questionhttp://manuals.info.apple.com/en/Boot_Camp_Install-Setup_10.6.pdf
create a Windows support software (drivers) CD or USB storage media
The Boot Camp Assistant can burn Boot Camp software (drivers) to a DVD or copy it to a USB storage device, such as a flash drive or hard drive. These are the only media you can use to install Boot Camp software.
- Installation Guide Instructions for all features and settings.
- Boot Camp 4.0 FAQ Get answers to commonly asked Boot Camp questions.
- Windows 7 FAQ Answers to commonly asked Windows 7 questions.