Sorry I'll have to disagree with the second two posts here.
You can bot a skill to 99. (I have a few, not combat however, but can be done.)
It is not an easy task. You need to find a method of your own as well as a script for yourself. There is an extremely large amount of data recorded on combat bots, yes even the premium scripts.
Find a location that is decent experience, away from any other location you will find any bot or any type. Record yourself training there for two hours. Then pay for a script to be wrote for you, as request every type of anti ban you can think of that may relate to your current playing patterns. Then request more and use a throwaway account to compare the script and your video of you playing. Babysit your new script for two hours.
Request any changes you may see fit.
Then your able to start botting. Run for around the same period of time you did your experiment. Babysit and message friends. Pause the script and let it auto log you out, etc.
Botting without a ban is possible. But takes money, research, and dedication which I'm not sure if you are willing to invest.