Yes, you may be able to manually create the Admin Pool accounts outside of the MNE Migration Manager console. Here are the steps:
1.) Create the MNE admin role group "MNE Migration Admin Pool Group" and assign the reqiured roles on the role group "MNE Migration Admin Pool Group":
ApplicationImpersonation
Distribution Groups
Mail Recipient Creation
Mail Recipients
Security Group Creation and Membership
2.) Create the admin account pool users as members of the role group "MNE Migration Admin Pool Group"
3.) Set the password for the Admin Pool users to the same password as the Exchange Admin in MNE so you can copy the MNE global setting ~AdminPassword= to ~AdminAcctPoolPassword=
4.) Be sure that the MNE global settings "AdminAcctPoolRoleGroupName=" is set to the role group "MNE Migration Admin Pool Group"
5.) On the MNE Exchange Server settings screen, click the admin account pool "Manage" button.
6.) Click Synchronize
7.) Click Close
8.) Enable the Admin Pool feature and migrate user data.