Develop a Kalman Filter to correct output from an accelerometer sensor

I need to create a Kalman Filter that will take input streams from different navigation sensors mounted in a vehicle like GPS, IMU and accelerometers and output the acceleration and position data. We are mostly interested in correcting the data from a vertical accelerometer when it is tilted forward, backwards and/or sideways.
We need the filter equations set up, software written in C and help implementing it.