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.
This plugin is available for download for your site.