Rewriting Mailman URLs

Rewriting Gurus,

I want to rewrite any Mailman URL that does not contain an underline, so that:

http://domain-name/mailman/script-name/list-name

is rewritten as

http://domain-name/mailman/script-name_domain-name

I almost have the solution but it fails for URL http://domain-name/mailman/script-name (e.g. http://domain-name/mailman/listinfo)

Here is the .htaccess file that I saved to the mailman cgi-bin directory:

RewriteEngine On

RewriteCond %{HTTP_HOST} ^(.*)$ [NC]
RewriteRule ^(.*)_(.*)$ - [L]

RewriteCond %{HTTP_HOST} ^(.*)$ [NC]
RewriteRule ^(.*)$ http://%1/mailman/$1_%1 [R=301,L]


These Rewriting rules fail for http://domain-name/mailman/listinfo

Any suggestions?

Thanks.

Jim