Trevor,
As you mentioned above, there is no UI for mass subscribing users to a team. The application console, however, should be helpful:
user_logins = ["john","jane","billy"] # Usernames for users being invited
team_name = "core-dev" # The name of the team
inviter = User.find_by_login!("trevor") # "Remember" who added the members
role = Role.member # Regular members, for admin members use Role.admin
group = Group.find_by_name!(team_name)
user_logins.each do | login |
user = User.find_by_login!(login)
membership = Membership.build_invitation(inviter, :group => group, :user => user, :role => role)
membership.save!
This is pretty much the same that the controller used in the UI will do, run it by going to the application root and enter
If this is something that needs to be done on a regular basis, id could be an idea to put it into a script (the script directory is well suited for this), perhaps prompting interactively for user names, team names and roles...