Might contact
support@lunarpages.com for more information on the specifics, however you can easily create the /webmail redirect yourself, and have it go to the client you want. For example:
Use appropriate link from LPCP, but the format for .htaccess is:
redirect /webmail https://216.227.220.35:20082/3rdparty/roundcubemail/index.php
You could also use just "/mail" too if you want. Also if you would rather use squirrel mail rather than roundcubemail, then just edit the .htaccess code above accordingly. Thanks!