The bootcfg command is a Microsoft Windows XP Recovery Console command that manipulates the Boot.ini file. This command has a function that can scan your hard disks for Microsoft Windows NT, Microsoft Windows 2000, and Windows XP installations, and then add them to an existing Boot.ini file or rebuild a new Boot.ini file, if one does not exist. The bootcfg command enables additional Boot.ini file parameters to be added to existing or new entries. To use the bootcfg command, start the Recovery Console with the Windows XP CD-ROM, and then click Recovery Console . Or, install the Recovery Console locally, and then select the command from the Boot menu.
Source:
Microsoft Knowledge Base