My mate Alex talked me into getting a smooth tailgate when I was buying the other parts for the bodykit from Online Tuning, and as this was the smallest part its what I practiced on first.

When the kit came it was already primed in white, but was a bit rough around the edges and also had a couple of deep scratches. 20 minutes later after using a 400 grade sanding block the panel was smooth again but also roughed up a little for the first coat of paint. Before painting it though I washed it in water to get rid of the fiberglass and paint dust. Whilst the panel was drying I started to remove the original tailgate panel. The lock came out easy as its held in place with a spring clip behind the interior plastic panel which just pulls off. With the lock loose I could get the metal rod from the lock out of the pushrod loop and throw the lot into the boot.
I know its not the right way but I got the panel off the tailgate by unclipping the plastic at the bottom edges and then pushing the panel upwards towards the window. It came off easily enough this way, but the plastic clips that hold the panel in place at the bottom became stressed and turned white but as I wasn't going to use it again it didn't matter.

I used cans of spray paint from Halfords to spray the kit with which Ive been told can be a bit dodgy but I was bored and gave it a go anyway, even though a mate from work offered to spray them properly for me. Off to halfords I went and bought a couple of cans of red plastic primer and Peugeot black. The plastic primer was sprayed on real thin so I could still just see the white fiberglass after three coats. My mate said before hand to use some form of heat to evaporate the thinners in each coat of paint that was sprayed, so out came the hairdryer and I used it every time I finished spraying a layer of paint on. I also used some halfords paint pads for sanding the fresh paint in between coats.  After about five thin layers of primer the panel was left until the next day to cure before I sprayed on the black.  Again I used the hairdryer between spraying layers of paint until it was all black and had a deep looking colour. After a fortnight I fitted the panel to my car using stickaflex to bond it on as the fiberglass panel doesn't have the original panel mounts. I also used stickaflex to fill any holes behind the panel and to fill around the boot lock because water had been leaking into the boot.

A week later (3 weeks since first sprayed) when I thought the paint had cured enough I used a rubbing compound on a wet cloth to cut back the final layer and give a even looking colour. After the whole car had been t-cut and waxed with the panel the colour match was near identical, much better than what id thought it would be.