You could use a PID to strafe and line yourself up horizontally with the pole.
- Mount your camera such that the center of the image is "straight ahead" for the robot.
- If you can see the end of the peg you want to hang on in your image, make the distance between that and the center of your image equal to the error.
- Strafe in the correct direction until the error is zero!
As far as stopping at the right forward position. You can use a triangulation method like Alan said. If you don't want to calculate anything, just see what vertical height of the target in your image corresponds to the forward position you are looking for. Set up a PID for that as well with the setpoint equal to that vertical position in your image.