you could remove the top cover on you central locking unit and solder it in direct like i have done in this image

wires in my pic are
black = gnd
red = +12v
blue/white = blue/black - (dead lock/central locking trigger)
but!
evocarlos said:
ive made 10 fitted one to my mates astra the central locking module did not have a black/blue wire so had to use the red/yellow now the windows shut on one push of the key fob witch he wanted lol
in your case

blue = +12v
brown = gnd
yellow/green = blue/black - (dead lock/central locking trigger)
its prolly best to have a look at this pdf also https://z22se.co.uk/guides/totalclosure.pdf
its been like 2years since i have been on this fourm so consicder your slef honnerd with my reply hehe 🙂
i do hope the info helps