Hi,
I just finished installing three hack/mods simultaneously. I did the intermittent wipers, spoiler switch, and US spec cigarette lighter. It took about a hour and half, plus two hours to try and figure out how to remove the cigarette lighter! I also wired everything up to the lighter to get the headlight illumination. It all works great, and I got rid of two more dummy switches. The spoiler switch is just for fun, but the intermittent wipers are a nice feature, and so is the new cigarette lighter.
It was a fairly simple job. I removed a few trim pieces and slid the radio out, but besides that it was simply running some wire and plugging everything in. Just thought I'd share!