You're playing with fire, period. You shouldn't do it, refrain from speaking about it or asking how to do it. If you have ever been the victim to negative SEO you know exactly how it feels and will agree when I say don't even bother with it. Your main priority should be making your campaign stronger to beat out the competition, regardless of what they are trying to utilize for their gains. Keep your ethics clean, and in the end you'll always come out ahead. Those who intend to cause harm or purposely try to destruct others hard work need to reconsider exactly what they are doing. Having a niche war is not fun guys.