[NTG-context] installing the letter module

Dear all This might be a trivial question for an expert user, but for an untrained end user this is not trivial, as I cannot find any documentation on wiki or anywere else. I would like to install the latest version of the letter module. How do I do this? I want to install it in a personal directory (say $(HOME)/usr/context/local-modules) and make sure that texexec will search this structure first before he tries to search the standard locations thanks stephen