"Cheating" requires three elements: Use of a feature not built into the game by design, competition, a level of deception.
If you use only features that were built into the game by design, even if you use them in novel or unconventional ways, you are not cheating. There is no rule book for AT, so the only set of rules are the ones dictated by the structure and features of the game. So using save games to deal with difficult monsters or rare drops is not cheating, even if some might consider it rather unethical. If you use only features that were built in to the game by design you are under no obligation to list all the features you used to get a particular score. If you exploit a bug, or use a feature that was not designed into the game (for example, editing your save game) you are still not necessarily cheating. It depends on whether or not you meet the other two requirements.
If you are playing the game entirely for yourself you can do whatever you want. After all, nobody else is being hurt by your actions, and you are not fooling anybody because of course you know what you have done. However, if you want to compare what you have done (e.g. your score, how many legendary items you have, etc) to what someone else has done then you are no longer acting in isolation. You are acting in competition, and competition is meaningless unless everyone plays by the same rules. Even if you used a feature that is not built into the game by design you are still not necessarily cheating though. As long as you openly declare what you did, anyone can take the comparison for what it's worth (depending on what you did, it could be worth nothing).
And that is where the last element comes in: deception. If you use features that were not built in to the game by design, and you compare what you have done in the game to what one or more others have done, and you don't declare that you used those features, you are cheating.
So you can use your bot to achieve whatever level you wish, but please do not post your characters stats in your signature, because other players will look at them under the assumption that you played by the same rules as everyone else, and if you used a bot to gain levels then that is not the case.
Like ctnbeh13, I don't see the point, and don't see any real distinction between using a bot in the way you describe and just editing the same game. The difference between you hitting the screen 1000 times and the bot doing it (or the mechanical finger, or someone else) is precisely that it's not you doing it. If I want to automate the grinding I could also download the source code and create a new version of the game, that only I have, that has a button called "advance one level". When I tap the button the computer just randomly kills things until I am one level higher. The fact that you have added such code outside of the game rather than in it makes no difference. As for paying someone, if you do that then it's no longer your character. It is, at least in part, that other persons character. If you then compare "your" character to someone else's without declaring that you paid someone to help you, then you are competing against them in a deceptive way, and that is cheating.
If in doubt, ask yourself "would this be fair, or allowed, in an exam"? Secretly using a computer to answer the exam questions for you is cheating. Secretly paying someone else to answer the exam questions for you is cheating. It would be an attempt to diminish the achievements of others by using deception to artificially improve your results relative to theirs. Of course, you could declare what you had done, but then your exam results would (rightly) be thrown out.
Edit: this is of course a personal opinion. What constitutes cheating is subjective, and I'm sure others will disagree with my analysis (or diatribe?). I tried to give the most objective opinion I could though
