Starting X with 8bpp

Hi, does anyone know how to start a second X server with just 8 bits per pixel. I am running the SuSE 7.1 XFree864.x mach64 server and have tried X -bpp 8 :1, but it starts a second server with apparently 24 bits. Using Sax2 I have configured the server for 24 bits, but it doesn't seem to be possible to set up both bit resolutions. Any ideas? David.