You don't. A PhD is a full-time job, a 40-60 hour/week one. I did the part-time Master's. That was a huge mistake. You will not get the education, the time to

You don't. A PhD is a full-time job, a 40-60 hour/week one. I did the part-time Master's. That was a huge mistake. You will not get the education, the time to research, the networking, the collaboration, or the presence to do the job right. A PhD done wrong is a waste of your time and the university's time.