You need to make sure they come with the cut-out template or whatever they are called if you decided to get it from e-bay (which is not recommended)
the template will have the location where you need to drill so you can attach the spoiler properly, it is definitely not something you wanna hold with 3m tapes.
You will get a set of hood struts as well if you order from the dealer, will help with the supported weight
Heres Simota1's DIY instruction for the insteall
DIY installation of genuine factory rear spoiler....