You should have done it when you were fitting your spoiler, It's so much easier to run the positive feed when you have full access to the wires.
If you do want to do it both wires to the spoiler brake light are I'm sure you'll remember black.
The positive feed is the thicker of the two.
I know mate was thinking that, can always unbolt the spoiler I suppose. Really fed up of ordering things from china though. The main reason I'd wanna do the mod is for the blue illumination but reading your previous comments I can't do that cause I'm not one of your lot lol.
Its a great little Mod Brigante and still working well
And Preee I'm blaming you for this one mate for making the guide or I'd have never got the idea. If I do decide to do it it'll be you the missus won't be happy with lol

would give Lenny a break I suppose