When starting a booking, choose the guest type from the traveler menu. After flights, hotels, or cars are selected, the purchase (or reservation) screen will allow you to enter an individual traveler's name and information. These itineraries will then appear in [Guest Type]'s Trips in the top yellow toolbar, as would any other traveler profile.
(If your guest-type does not appear in the pull-down menu, create one first as shown in the earlier section.)

After a guest account type is created, it can be managed in the Guest List under its own tab:
