The usual (and some new modules).
diff --git a/Lib/dos-8x3/sitecust.py b/Lib/dos-8x3/sitecust.py
new file mode 100644
index 0000000..c5ac13d
--- /dev/null
+++ b/Lib/dos-8x3/sitecust.py
@@ -0,0 +1,2 @@
+import sys
+sys.modules['ni'] = sys.modules[__name__]