That would be the Halo B. By any chance do you know if it has a V35 board or not?
If you aren't sure, try to follow these instructions anyways:
To enter programming mode, while the loader is OFF, press and hold the power button for 5 seconds and the LED begins to flash. Release the button. The LED will flash the current speed selected in green followed by one red flash to indicate the end, then repeat. After 10 seconds of no activity, the loader will exit programming mode and turn OFF. The default speed is Speed 3.
Speed 1 17 BPS
Speed 2 21 BPS
Speed 3 24 BPS
Speed 4 28 BPS
Speed 5 32 BPS
Speed 6 35 BPS
Once in programming mode, each time the button is pressed the program advances 1 speed setting. Press the button once for each advancement desired. Once at Speed 6, an additional button press will cycle the speed setting around to Speed 1 again. After each button press, the LED will begin flashing the new speed setting. When you have advanced to the setting you would like, do not press the button any further and after 10 seconds of no activity the loader will exit programming mode and turn OFF.
EXAMPLE - If you are in Speed 3 and you press the button 2 times, you will now be in Speed 5. If you are in Speed 5 and you press the button 3 times, you will now be in Speed 2.
Note: Disconnecting the batteries will reset the speed setting back to default, which is Speed 3.