Reverse hub motor rotation

[omtrevor]

I need to temporarily put my etrike hub motor in reverse from time to time.Just to travlel a few metres for a few seconds,then switch back to forward as usual.I am partly disabled and need the trike to go backwards to make life easier.If I can switch off the hall sensors using relays and reverse the polarity of motor power leads and changing over two phase leads,also using relays,do you think this would work without damaging the controller? It would take several relays which could all be cotrolled with one forward/reverse switch.Good idea,or am I sober again?!