How do I include get an import code to include on my employees W-2?

An import code for what?  So they can import it to Turbo Tax?  Are you signed up as a Turbo Tax partner?  It uses your EIN.

https://www.partner.turbotax.com/top_partner_list.html 

If you are using INTUIT payroll you need to ask them ...  

Here's how to sign up and and register to view your paycheck ...

1. Ask your employer to invite you for QuickBooks Workforce.
   Here's the link: Invite employees to view paychecks and W-2’s online.
2. Accept the invitation through email to create your own Intuit account.
3. Go to your browser, then sign in to workforce.intuit.com.
4. View the paycheck by clicking the Paycheck menu.
5. Then, download and print your paycheck.

Once done, you can go to the QuickBooks Workforce: Access your paychecks and W-2’s online.