for startup config file example,
#pci0=0,video,0; not activated yet
#video=cofb:1024x768x32
video=cofb:800x600x32
#video=cofb:off
#video_mem=4096, not used obsolete cofb parameter, replaced by cofb_mem0
#cofb_mem0 to config.video_devs[0].size KB
cofb_mem0=4096

Use cofb under X window (based on usage on debian distribution)
framebuffer X driver, install xserver-xorg-video-fbdev from aptitude

To let detect X auto detect mouse
ln -s /dev/input/mouse0 /dev/mouse
To disable X window mouse acceleration.
xset m 1 0