Gooooooood luck with that one!
You can read about my escapades in the same situation.
http://www.canreef.com/vbulletin/showthread.php?t=27132
If it's any consolation, although I gave up trying to remove my sixline (he is just way too smart to fall for any trap or be fished out, and far too fast to be netted out), he's better behaved towards the newest-addition (potter's angel) now, so I don't feel the pressure anymore to remove and isolate him like I did at the beginning of that thread. Although I still have my fishing rig ready to go "just in case." (I had to get a very small hook from a fishing store, they looked at me like they thought I was an idiot, going in there and asking for "one hook please.")
Of course I have tankmates in there that shouldn't theoretically be threatened by a sixline smaller than them anyhow. Smaller fish might be at perpetual risk so you might need to remove him if you can. I know my sixline is responsible for killing a mandarin, I imagine a small goby wouldn't fare a lot better in a full out assault like what happened there. (Stupid fish..)