i did mine the other day mate.was really easy to do. jack the front end up.mark the middle of the bumper with something, dont sratch it obviusly use tape or something.line the middle of the splitter up with the middle of the bumper and mark where the tabs on the top of the bumper (where you are going to screw through) are on the splitter in conjustion with the bumper. you will need to trim a slight bit off the 2 parts of the splitter which stick up in the middle just to make them flush so they fit properly. make the both the same size or the bumper will be lob sided when you screw it on.
drill some small holes it the splitter and bumper (bumper is optional but will make it slightly easier)
fit self tapping screws through the holes on the splitter and marry them up to bumper.get the more central 2 in first then work your way out to the side from there.
you will notice that the splitter is slightly too long where it meets the wheel arch, just trim it with a small saw and smooth the edge off with a heat gun.
hope this helps you pal because it took me ages to write it haha!
jacko