This is an overview of my process for building a corporate brand. The way I work is framed by one school of sociological theory, "symbolic interactionism" (SI).
More on that in a minute.
The main difference between corporate branding and product branding is the development institutional capacity. In product branding your focus is outward, whereas on the organization side it's holistic. Internal and external stakeholders are equally important, and you get your message across in three ways:
1) What you say (content)
2) How you act (culture)
3) Doing things the same way repeatedly (consistency)
The reason you need sociological theory, specifically SI, is that more often than not there is a disconnect between the message the organization sends out (or the messages, which are frequently discordant) and the perceptions that key audiences have of it.
SI attacks that problem by putting your self-perception (the "I") into a dialogue with the perceptions that others have of you (the "me.")
When you have a good flow of dialogue, that is organizational mental health and the communication decisions that get made are more likely to move the brand forward (increase its value over and above a commodity).
There is a more advanced level of SI that addresses the interaction between self and perception - if you're interested you may want to read the work of Georg Simmel. I wrote a paper about this a while back, and you can download it here (fee).