There are several ways to tell GnuPG a custom keyring location.
- Move .gnupg and set GNUPGHOME to the new location
- Move .gnupg and use –homedir=<dir> on every invocation of GnuPG
- Leave .gnupg, only move the keyring and set path to gpg.conf:
no-default-keyring primary-keyring <dir>/pubring.gpg secret-keyring <dir>/secring.gpg trustdb-name <dir>/trustdb.gpg keyring <dir>/pubring.gpg