Rather than using the port 2222, I hope to force my customer by using SSL protocol to the DA panel with URL of https://subdomain.mydomain.com . How can I do?
It can't because it's a separate daemon; it doesn't use httpd.
And two deamons cannot bind to the same port at the same time.
You can create your own login page, anywhere (see other threads in these forums), but DA will still have to operate either on port 2222 or another port you select (see other threads in these forums for this information as well).