Unless you already have connections within the hanamachi it is very very unlikely that a foreign woman, or even a woman at all could hire a Geisha. They are very expensive, usually only entertain for male patrons, and usually only at specific tea houses or banquet halls. Sometimes arrangements can be made, nothing is impossible, simply unlikely.
Today the highest population of Geisha are found in Kyoto, Japan. The Geisha district of Kyoto is known as the Hanamachi, which means 'flower towns'. Those districts are; Gion, Pontocho, Kamishichiken, Gion Higashi, and Miyagawa. There are other Geisha districts around Japan like the Higashi Chayagai, Nishi Chayagai, and Kazuemachi districts in Kanazawa; and Asakusa in Tokyo.