Where is the procedure for installing additional locales documented?

I'm working on an app that needs to read strings from a binary file written on Windows (a Visual Source Safe database) and write them to an XML file. I want to write the XML in the same codepage using TinyXML, and it uses the isprint() function to filter invalid characters, so I need LC_CTYPE set appropriately. I found that the strings in my test data were from codepage 1252, but other users will see their native codepage. The XML will be read into a Perl script and eventually written back out to a UTF-8 file (a Subversion dump file).

After lots of digging around in the glibc source I found I needed to use localepref to build /usr/lib/locale/en_US.CP1252 from the files in the localedata subdirectory of the glibc sources. But when I run "locale -m" I do see CP1252 listed. That suggests that there's some way to install a new locale without having to install the glibc source. (I'm doing this through an ssh terminal session, so hopefully I don't need an X app for this.)

I also found /usr/share/locale. What's the relationship between this directory and /usr/lib/locale?