My own interpritation, and by no means is it watertight, is that no, this would not be legal nor in the spirit of the rules.
The rules regarding the ball chute are pretty clear. The rules regarding operators and 'devices or clothing' that would give a competitive advantage are also pretty clear. While I have never considered the use of glue, I would feel that it would fall under the same catagory as devices or clothing that would give a competitive advantage, and thus be illegal.
Again, that's how I look at it. Perhaps I am misreading the rules- I don't think I am. Perhaps I am taking them to broadly. The problem is in the wording, which doesn't fully cover what you're preposing. Only an update from FIRST and/or the ruling of a Ref at the site could really tell you if it is legal or not. The suction cup idea, I can all but promise you is illegal. Since it isn't controlling a robot function, there is really no way to justify bringing it to the field under the rules. In fact, the rules on that one are pretty open and shut.
Regardless, I wouldn't do it. I am willing to do a lot of things for my team. Slathering my hand up in rubber cement all day is just not one of them.
Interestingly, the game orignaly called for some sort of stick or padle the human player could use to grab balls. I really don't recall just what it was for or why it was removed from the game at the last second.
-Andy A.