I have a wired thermostat downstairs (rather than the wireless one in the OP) and so according to my basic knowledge of wiring and the manual above, should be the existing connection. Hoping the OP can confirm his was working correctly afterwards which would give me a bit more confidence to do it.
I'm about to do the same - Did imiller9 have it correct? Assuming you disconnect ribbon and ignore, then take out the Ls & Lr into Hive? Please let me know, as Worcester won't do it.
Also, does yours already have a connection to the Ls & Lr? I think it is for the old thermostat which would mean...