[Ryan Ashbrook]

I use this method, you can try it but I can't garauntee it'll work without some adjustments.

Create a plugin and place it on the global_start hook with the following code:

PHP Code:

if ( preg_match ( '#\/~name\/\/forums\/#ise', $_SERVER['REQUEST_URI'] ) )
{
    $uri = str_replace ( '/~name/forums/', '', $_SERVER['REQUEST_URI'] );
    header ( 'Location: http://www.mysite.com/forums/' . $uri, TRUE, 301 );
} 


Remember to replace all instances of ~name and mysite.com with what they should be.