In the plugin, create an additional phrase called "flashchat_path" and set it to "/chat/".
Then try altering the XML as per the following example ;
Code:
<navoption>
<phrase>flashchat_menu1</phrase>
<link>$vbphrase[flashchat_path]admin/msglist.php?{$rand}</link>
</navoption>
I haven't tested this, but it should work, allowing people to edit the flashchat_path phrase to suit their installation.