Prasad has an interesting post on the various pulls and pushes that the HR function (and indeed, any support function) faces in a partnership firm.
Thus some of the partners might view well defined HR processes as impediments to their 'freedom of operation'. This might pull the firm towards functioning like a 'family owned firm'.
However, most of the global partnership firms have well designed global HR processes. It is essential to have these processes to manage the scale of operations and to attract and retain good talent. Also one of the key attractions for working in a partnership is the opportunity to grow in the firm and become a partner/owner. Well designed HR processes are required to facilitate this and to give the employees the 'comfort feel' that this is possible .
The key is the desire of the partners to have it in the first place, and looking at their roles themselves as that of grooming future partners. If that does not happen then HR gets reduced to recruiting and resource management roles without looking at development and growth.