Are you talking about from a floppy or like how it was done with windows 9x?
The thing about windows 2000 was that they didn't include dos, instead decided to just emulate a dos envirorment instead of just building windows atop of dos.
So no you cannot really boot into dos. Besides if your using ntfs you would need a special build of dos to view ntfs.
You still can with a bootable floppy, but there isn't a need to these days.
If you must do so for some reason use this site:
http://www.bootdisk.com/
There is a boot disk that you can make in windows 2000 by selecting add boot files when formating a floppy you can boot into a dos envirornment, except for dos is pretty much obsolete these days..