Unless you've stripped the Eadmin account of the {default administrator} COS, you can do that. You'll need to give that account a password first, of course. Or you can find another account which doesn't have a unity-enabled mailbox and use grantunityaccess to associate it with the Installer.
grantunityaccess -u DOMAIN\useraccount -s Installer
This is the syntax. Just replace DOMAIN\useraccount with your domain and user account.
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