This is a somewhat difficult question to answer. Just because someone is a T in their personality type does not mean they are smart or even capable. The T/F dichotomy is merely HOW you make your decisions. To quote another website:
"Thinking types tend to make their decisions based on data, evidence and rational thought. They tend to be pragmatic and not swayed by antipathies or emotions but prefer empirical data.
Feeling types tend to make their decisions based on values, emotions and impact on people. This is a slightly more illogical way of making decisions (when compared to logical ‘T’s) however ‘F’s can often ‘feel’ situations and so their decisions often take account of the less obvious more subtle issues that transcend the logical."
I think INTJ's tend to be very logical and motivated by what they think the world is, and that's how they act on it. They are good at predicting how systems will progress and emerge. I am a borderline INFJ / INTJ. I have worked in the IT field for almost 3 decades and can say that I know many people who are INTJ, most of whom I don't trust to do the right thing. The reason I say this is because a true INTJ doesn't always make decisions based on what is best for people. Look up some of the INTJ's that are /have been famous. If an INTJ's moral compass is skewed from early childhood then they can become a very dangerous person. This is because they will make and implement systems without regard to what is good for people. Sure, they may make a lot of money but possibly only at the expense of many people getting hurt. Lots of big CEO's in this category.
I like being an INFJ. I care about people and that is at the forefront of who I am when I make decisions.
To answer your question. If you want to become more INTJ from an INFJ then you would likely need to destroy part of the feeling part of your self. Stop caring about people and make logic as your primary means of decision making and then you will become more INTJ. But I will say this, be careful what you wish for, it just might happen.