Sorry guys been gone for a long time now since been working on my Tacoma. To answer your question to install the spoiler I remember circle double sided tape I think. And there were also other 3m double sided tape. Another reason I stopped posting here was because the forum said I met my photo quota and not sure how I can get past this to post all the fun pictures of my ride. I hope your spoiler turned out well by the way.
I ordered a tube of the sealant that the instructions said to use. It just arrived today so now I'm just waiting on a warmer day to get it installed.
Good luck. It's not a hard install, just a little time consuming. Did you ever get the template? By the way thanks for posting before on the DNA exhaust. I've been running it for last month with the TRD intake and it's an excellent combo. Throttle response is improved for sure.