NT Domains

No, DCPROMO does not work in NT4.
Use Server Manager to upgrade a BDC to PDC.

And in regards to Win2K Domain Controllers and NT domains, it depends on if you have an existing NT domain, or if you want to make a new domain.
If you have an existing NT domain, and you want to have only Win2K Domain Controllers running it, then you have to upgrade your NT4 PDC and BDCs to Windows 2000. When you do that, then the NT4 domain is upgraded to a Win2K Active Directory domain.
Now, if your goal is to remove the machines that are currently your NT4 PDC and BDCs with new machines running Win2K, then still upgrade the NT4 PDC and BDCs to Win2K. After that, add the new Win2K machines and make them Domain Controllers also. After that, you can DEMOTE your original NT domain controllers (that were upgraded to Win2K Domain Controllers), leaving only the new Win2K machines as Domain Controllers.

Either way, when you start the DCPROMO process on whatever machine you run it on, you have to selectthat the domain will be used by Pre-Windows 2000 clients (this is the default setting). This means that the PDC Emulator Operational Role will be assigned, and with it, NT4 Workstations and NT4 Member Servers can be added to the Active Directory domain.

hope this helps