By superglue gel, not sure what you mean. If you mean just normal superglu, then I'm sure its okay. I have cut my lip, arm, fingers, face, etc.. and used superglu instead of bandaids.. My father taught it to me after he found out that they use cayaniocrilliate (spelling!?!) in surgury at all hospitals to heal internal wounds that need to be sealed wet/bloody (you know what I mean). So, if its good enough to be inside the human body and sewed up inside, I would imagine it would be okay to put in an aquarium.
I would, however, do like mentioned and put it in a bucket first to make sure no residue gets thrown around at all.. You can clean it up before you place it in the tank permanently.
I am not a pro.. I'm quite the beginner.. don't even have my tank set up yet and have never done salt-water.. HOWEVER, I know a pretty good deal about adhesives.