make sure that port 3306 is open on firewall
then in DA under MySQL there is section to manage the remote ip address.
You can add a new user via phpmyadmin (logging in as root)
and use a % in the host box
so every host kan remotly login to your mysql server
You can use DirectAdmin too to change users external host.
Login in DirectAdmin
Goto "MySQL Management"
Select the user that must have external login permitions.
And type in the host box a % character,
press add to finish.
Now you can login remotly with that user.
Dries