Allow overriding of bgen pathnames in an optional module bgenlocationcustomize.
Editing of bgenlocations.py isn't easy if your Python was supplied by Apple.
diff --git a/Lib/plat-mac/bgenlocations.py b/Lib/plat-mac/bgenlocations.py
index d4f2d70..19e1f02 100644
--- a/Lib/plat-mac/bgenlocations.py
+++ b/Lib/plat-mac/bgenlocations.py
@@ -31,6 +31,14 @@
 # Creator for C files:
 CREATOR="CWIE"
 
+# The previous definitions can be overriden by creating a module 
+# bgenlocationscustomize.py and putting it in site-packages (or anywere else 
+# on sys.path, actually)
+try:
+	from bgenlocationscustomize import *
+except ImportError:
+	pass
+
 if not os.path.exists(BGENDIR):
     raise Error, "Please fix bgenlocations.py, BGENDIR does not exist: %s" % BGENDIR
 if not os.path.exists(INCLUDEDIR):