Zbuffer and 1/z-s


I am on my way to code the opengl port of our glide based game. Well, almost everything runs fine, but:

The voodoo version is optimised for using 1/z buffer as depth buffer. For now I am converting all the cordinates to use them as Z-s. It is working fine, but after a certain distance when two polygons intersects I get lots of Z buffer bugs.

Is there a way to set up the depth testing to act as a 1/z buffer? (I tried but get nothing - there was no polygons on my screen).