I set this up a couple of weeks ago and the one thing that you didn't mention is that you need something to clear target as part of your steps. If toons have a target and are not mousing over something they can interact with, and the target is close enough to interact with, they'll run off and try to interact with it. Learned this when trying to fish in SW next to the trainer! All the other steps Ualaa mentioned are part of the system I have going for fishing and it works great!

I found it easiest to just put the /cleartarget on the IWM key.