You will not be able to use anything but the supported adapters because the drivers will not be available for any other cards.

They must also be genuine IBM cards or the driver will not configure it because it will do a vpd lookup on the card and if the vpd is not from IBM the driver will not configure it.

For instance some of the gxt cards are made by matrox and then ibm re-write the vpd. if you stick the original (pc) matrox card in, same card hardware but without the modified ibm vpd, the driver will fail to load.

If you don't have a graphics card you can still install X11 and export the display to another system with a graphics card, then display the CDE on your graphics console from the other machine.