is there a CV64/3D sounding monitor icon in your devs:monitors folder?
there is a fair chance you will have to go into CGXTools and tell it what kind of monitor you have (or near approximation), it will then fill out the screen modes in CGXtools, or you can configure them yourself, and (once saved and rebooted) these screen modes will appear in screenmode prefs.
its a pain to set up, but it does offer good flexability once you get the hang of it.
-edit-
CGX4 is mainly bug fixes, speedups, code optimizations, and additional drivers for more GFX cards (namely the C/BvisionPPC).
i ran a cyb2-040 A4000D with KS3.0, WB3.0, and a cv64/3d with CGX3 during my time at uni and never had any probs.