After a fair amount of experimentation, I finally was able to make Carmageddon word under Win 2000 by doing the following:
1. Install Carmageddon 2 from CD. Apply 2.0 Patch (see ftp.avault.com/patches/c2ptch12.exe).
2. Put Glide2x.dll in the Carmageddon directory (unclear whether this is necessary, but I did it).
3. Run UnSafeDisc 1.5.5 (see http://gamefix.moax.com/files/unsafediscv1.5.5.zip) on Carma2_HW replace Carma2.HW.EXE with whichever of Testme.exe or Testme2!.exe works. Don't worry if you get a BRender Error when you run this file directly (i.e. not from Carma2.exe).
4. Run UnSafeDisc 1.5.5 on Carma2_SW replace Carma2.SW.EXE with whichever of Testme.exe or Testme2!.exe works.
5. You should now be able to run Carma2.exe and play Carmageddon 2 under Windows 2000.