Even when “I” isn’t permitted, it’s still possible to convey a sense of I-ness. The political columnist James Reston didn’t use “I” in his columns; yet I had a good idea of what kind of person he was, and I could say the same of many other essayists and reporters. Good writers are visible just behind their words. If you aren’t allowed to use “I,” at least think “I” while you write, or write the first draft in the first person and then take the “I”s out. It will warm up your impersonal style.