I'm not familiar with any part-time medical schools
. Even full-time, the process would take a long time. Typically the nurse would have to:
- Earn a four-year degree if he/she did not already have one.
- Complete the pre-med prerequisites (possibly in conjunction with completing the four year degree). These would usually include two semesters of chemistry, two semesters of organic chemistry, two semesters of physics, two semesters of intro biology, two semesters of advanced bio courses, and others, depending on the program.
- Complete four years of medical school.
- Complete postgraduate education (internship/residency in psychiatry) of ~5 yrs.
For US-based programs, there's really no 'partial credit' or 'fast track' for nurses who want to become physicians.