On my MP Edge, reverse is enabled by default and the default speed for reverse is set at 65rpm (forward default speed is 380rpm).
This should give you a speed in reverse of 5~9km/h dependant upon your wheel size. If you wanted to go any faster in reverse you would need either the USB programming lead, Windows PC/laptop and PI800 programming software, or the Bluetooth dongle, a suitable smart phone and the GM App.
Alan