Windows 98, 98SE, and ME operating systems will not dual-boot with Windows 2K unless they are installed before[/] Win2K and are on the primary partition. Even if you can get WinME to install on a different partition, you'll need 3rd party software to allow you to boot to that drive.
The problem is that Win2K takes control of the "volume" information on a hard drive. When you install Win2K after installing WinME, 2K will see that WinME is installed and modify the boot sector of the drive to work for both. WinME does not have this capability.