We'll create fresh WordPress site with Custom Shortlink Structure installed. You have 20 minutes to test the plugin after that site we'll be deleted.
This plugin will add new settings to your Settings -> Permalinks screen for you to
specify your blog’s shortlink structure. By default WordPress shortlinks look like
http://yrnxt.com/?p=153. Using this plugin you can specify every other structure
you like, e.g. http://yrnxt.com/~153.
Specifying new shortlink structures will never break WordPress’ default. Also when
changing the shortlink structure again afterwards old structures won’t break until you
explicitly remove them.
Take a look at the screenshots.