Did you mean to have good psychology in trading? To have it , i think we not need to do meditation. We should be keep learn and learn to more to understanding price action and to know all risk of trading, and we should be minimize the risk by make risk management . I dont see any relation between trading and meditation.
Sometimes, I even tend to wonder how people tend to find an explanation to things and you are right, there is absolutely no relationship between meditation and trading as far as I can tell. At least, I am a trader, I am doing very well, and I have never meditated, so I do not even see it as any criteria at all. What makes sense most of the time, is to know exactly what you are doing, and make sure you always have a plan when you are trading, which you cannot do all these without having some knowledge.
The truth is that as much as you want to meditate, if you leave out the first few things you need to do before starting to trade, when it comes to learning and practicing, you will never stop getting emotional and no matter the meditation you waste your time doing, it would not stop you from being emotional as you will lose no matter what.