Decide what field you would like your PhD to be in. Write a list of goals for the degree and subjects you feel you would need to study, as well as a proposed dissertation topic. For instance, if you want a PhD in 16th century American women's history, you might note that you hope to have a master understanding of the social, cultural and historical issues facing women of the time period. You may want to study subjects like dress and fashion or literature, and you may propose to research political events in which women had a direct hand.
Create a list of schools you would like to attend. Don't simply list Ivy League or big-name schools, but examine the faculty and PhD programs at each individual school. Find schools where faculty specialize in your research interests or schools that house faculty members whose books you noted with special distinction. Write a list of at least 10 schools, as not all of them will be willing to allow you to create your own PhD program.
Carefully examine the PhD program offerings to make sure no program corresponds with your research interests. In some cases, you may be able to choose a broader program and specialize through the courses you take and your dissertation.
Check to see whether the university of your choice offers an individualized PhD program. If so, read the rules for applying; then submit an application. For instance, the University of Washington requires that individuals complete a Master's Degree or be current University of Washington graduate students who have almost finished their programs to apply. Non-University of Washington graduate students also must pay an application fee.
Meet with an adviser to determine your course. Work with a qualified adviser in your field to plan your program. You and the adviser will determine whether the university can offer your program, plan your courses and discuss possible dissertations.