Finding time to produce scholarship while working full-time as a lawyer can be a difficult challenge.  Increasingly, law schools offer one or two-year fellowships that afford prospective candidates an opportunity to research, write, receive mentoring from senior faculty, and soak up the atmosphere of a law faculty.  Some of these carry teaching obligations (which itself can be a valuable experience and an aid in obtaining a full-time position, provided you get your writing done).  Below is a partial list. 

Chicago: Bigelow Program

Columbia: Academic Fellows, Associates Program, Center for Reproductive Rights-Columbia Fellowship, Columbia Law Review Milligan Fellowship

Georgetown: Fellowships

Harvard: Fellowships, Climenko Fellowship, Visiting Assistant Professor

NYU: Furman Fellowship Program, Lawyering Program, Furman Center Fellowship (third on list at link)

Northwestern: Visiting Assistant Professors and Fellows

Stanford: Legal Research and Writing Program

U. Texas at Austin: Emerging Scholars Program

Yale: Ruebhausen and Ribicoff Fellowships