I haven't used the Aerox one, but have set up the Aprilia SR one - it was a piece of piss... I would think they are very similar.
I would recommend disconnecting your speedo cable at the wheel end first as it is a lot easier to fit back to the wheel than to fiddle with the instrument end
The only thing missing from the kit was a couple of small cable ties to secure the revcounter sender wire... I wrapped it half a dozen times round the HT lead, then cable tied it at both ends of the spiral, then trimmed the end.
IMHO a very attractive and accurate upgrade... the speedo certainly seems more accurate than the POS items shipped as stock.