When classroom teachers introduce curricular innovations that conflict with their former deeply rooted practices, the teachers themselves experience a process of change. One professional development framework intended to support this change is the customization workshop, in which teachers cooperatively customize innovations to their own classroom contexts, reflect on the strengths and weaknesses of classroom implementation, and refine their innovations. Two goals sometimes conflict in such workshops: developing teachers' skills as reflective practitioners (process) and maintaining crucial characteristics of the original innovations (product). This paper explores how to meet both challenges using the insights from a perspective that provides a striking parallel: developing expertlike problem-solving skills (process) as well as conceptual understanding (product) in the physics classroom. We apply this perspective by (a) characterizing an expertlike approach to pedagogical problem solving in the context of customization workshops, (b) determining the nature of pedagogical problems best suited for developing such an expertlike approach, (c) suggesting how to design customization workshops that support teachers to develop an expertlike approach to pedagogical problem solving. In particular, we hypothesize that applying cognitive apprenticeship in customization workshops in a manner similar to its application in the teaching of expertlike problem solving in the physics classroom should effectively help teachers approach the pedagogical problem of customization in an expertlike manner. We support our hypothesis with an empirical study of three year-long cooperative customization workshops for physics teachers that differed in terms of mentoring approach. We examined the questions (a) under which mentoring approaches did teachers perform an expertlike pedagogical problem-solving process and (b) which practices and perceptions emerged through execution of this process?