Well I just installed my spoiler today. I went ahead and used the betalink. The stuff is really sticky and can get everywhere if your not careful. It very much so resembles tar for those who are unfamiliar.
It is a very good thing that the betalink kit came with betacleaner because that stuff works really well to clean off all of the extra goop.
Anyway, it came out looking really good! I will post a pict tomorrow.