Here is a solution that worked for me.
I have Mandrake 10, kernel 2.6.3-16 and a GForce4.
Step 0. NO need to modify your nv.c file, NO need to patch things, NO need to install mysterious pre-compiled kernels.
Step 1. run the 6111 package with the option --add-this-kernel (as suggested elsewhere in this forum)
this creates, after some stressful minutes, a "custom" package.
Step 2. run the custom package with no options.
Note: I was having the usual problems (fail to build, rivafb, make mrproper in log) so I no-ed the rivafb options in my kernel. I don't know if leaving them on Y or M will interfere with these instructions.