One way.........

Make a stalagtite/mite object in your modeler of choice. low poly of course and with an appropriate texture. Import to Vue and save as .vob.

Create a terrain and sculpt it for your cavern floor however you wish it.  Texture and populate with your stalag object. Variate the size, density and distribution.

You can simply duplicate this terrain and flip it over and above the first one......or create a separate cavern ceiling terrain and follow the same steps.

Adjust your lighting and atmosphere to taste.