You can register any email address with Google here: http://goo.gl/zGc2vC.
For multiple admin accounts of the same enterprise, we advise to set up a dedicated Google Apps account. This Google Apps account allows central management of the dINK administrators, with full control over adding and withdrawing access rights.
The domain you create should be different from your company’s domain. So you could create a Google Apps account for companyname_dink.com (just add dink to your company name) and create users like firstname.name@companyname_dink.com.
Here’s the link to Google Apps registration: https://www.google.com/a/signup/. First month is free, aftwards cost per year is only 40EUR.