Index: src/zope/i18n/zcml.py
===================================================================
--- src/zope/i18n/zcml.py	(revision 103877)
+++ src/zope/i18n/zcml.py	(working copy)
@@ -1,4 +1,5 @@
 
+
 # ##############################################################################
 #
 # Copyright (c) 2001, 2002 Zope Corporation and Contributors.
@@ -50,13 +51,14 @@
     return lang in config.ALLOWED_LANGUAGES
 
 
-def handler(catalogs, name):
+def handler(catalogs, name, factory=None):
     """ special handler handling the merging of two message catalogs """
     gsm = getGlobalSiteManager()
     # Try to get an existing domain and add the given catalogs to it
+    factory = factory or TranslationDomain
     domain = queryUtility(ITranslationDomain, name)
     if domain is None:
-        domain = TranslationDomain(name)
+        domain = factory(name)
         gsm.registerUtility(domain, ITranslationDomain, name=name)
     for catalog in catalogs:
         domain.addCatalog(catalog)
@@ -64,7 +66,7 @@
     domain.addCatalog(TestMessageCatalog(name))
 
 
-def registerTranslations(_context, directory):
+def registerTranslations(_context, directory, _factory=None):
     path = os.path.normpath(directory)
     domains = {}
 
@@ -101,7 +103,7 @@
         _context.action(
             discriminator = None,
             callable = handler,
-            args = (catalogs, name))
+            args = (catalogs, name, _factory))
 
     # also register the interface for the translation utilities
     provides = ITranslationDomain