Hello–
We did not bring over the ‘manage domains’ format to IW7, as it tended to be confusing to a lot of customers. Everything is based on dropdowns on the individual pages, now. For example, to create an email address for a secondary domain, you would just choose it from the dropdown on the creation form:
To view the mailboxes for a secondary domain, you would choose it from the dropdown on the mailbox page:
For databases, it is a little different as there never really was a difference in what what shown or accessible depending on which domain one was logged in as. All databases on a SiteWorx account are prefixed with the unixuser, and all were able to be seen on the mysql database page. Secondary domains never actually had their own, specific databases, they way they do email addresses or SSL certificates.
For example, on my IW6 test server. I have two domains on an account–the main domain is test.com. The secondary domain is second.com.
While logged in as second.com, I created a database, which was named testcom_seconddb. While logged in as test.com, I created a database, which was named testcom_maintest. Both are listed on the MySql page, no matter which domain I’m logged in as.
In fact, while logged in as second.com, when I navigate to Hosting Features > MySQL > Databases, it automatically switches back to test.com for that page, since secondary domains to not actually have their own, specific databases.

And, when I access PHP MyAdmin while logged in as second.com, both are listed there, as well:

When you say that you need to access the MySQL for secondary domains, can you provide a bit more detail? Are you missing databases from the MySQL page? Are you missing them in PHPMyAdmin? Are you trying to create a database specific to the secondary domain?
Thanks,
-Jenna