Maintenance page and localhost access

[Ian M. Evans]

As I prepare to test some changes related to the "0day exploit" thread, 
I thought I'd set up a maintenance page block so I could do the testing.

Just realized though that the maintenance block examples take the site 
down for everyone.

How do you serve the maintenance page to visitors will still allowing 
localhost access.

Should I just create a new server block listening on another port and 
deny all, allow 127.0.0.1?