disable mouse acceleration on mac os x

mousekiller.c

/**
*  to build: gcc -o mousekiller mousekiller.c -framework CoreFoundation -framework IOKit
*/

#include <stdio.h>
#include <IOKit/hidsystem/IOHIDLib.h>
#include <IOKit/hidsystem/IOHIDParameter.h>

int main(int argc, char **argv)
{
   const int32_t accel = -0x10000; // if this ever becomes a scale factor, we set it to one
   if(argc < 2) {
      fprintf(stderr, "Give me mouse and/or trackpad as arguments\n");
      return 1;
   }
   
   io_connect_t handle = NXOpenEventStatus();
   if(handle) {
      int i;
      for(i=1; i<argc; i++) {
         CFStringRef type = 0;
         
         if(strcmp(argv[i], "mouse") == 0)
            type = CFSTR(kIOHIDMouseAccelerationType);
         else if(strcmp(argv[i], "trackpad") == 0)
            type = CFSTR(kIOHIDTrackpadAccelerationType);
         
         if(type && IOHIDSetParameter(handle, type, &accel, sizeof accel) != KERN_SUCCESS)
            fprintf(stderr, "Failed to kill %s accel\n", argv[i]);
      }
      NXCloseEventStatus(handle);
   } else
      fprintf(stderr, "No handle\n");
   
   return 0;
}

Credit to these guys:
http://forums.macrumors.com/showthread.php?t=361844