Hi,
What do you wish to do, exactly? Assuming you are using the W2K boot manager and not a third party boot manager, it seems as though you wish to edit the boot menu (not the loader). If you wish merely to change the default boot partition, you can right-click on "My Computer", select "Properties" from the context menu, select the "Advanced" tab on the "System Properties" dialog box, click on the "Startup and Recover" button on that page, then choose the "Default operating system" from the drop-down list. You'll also see an option just below the drop-down list for turning the menu list on and off, and for setting how long it displays before it boots the default OS.
If you wish to change the wording of the boot menu, or the syntax of any of the menu's options, you'd have to edit the boot.ini file. You'd want to do some careful research before doing that because it's fairly easy to give yourself some boot-time headaches by editing that file. It's not rocket science at all, but you can't just change things in the file willy-nilly.
Regards,
Jim
Edit: Ooops! Slow fingers!