Im not sure if it will work on the current phpmyadmin path since when i tested that dosent work for me and i had to move phpmyadmin into my httdocs folder to make it work and it's better because you can change de rout like
http://localhost/SecretPhpMyAdmin or something anyway just move it and make an .htaccess
Code:
<Limit GET POST>
order deny,allow
deny from all
allow from 127.0.0.1
</Limit>
Probb there is other ways and more easy but that the one i used..
EDIT: You have to log with localhost or 127.0.0.1