You can enrol someone into a Unit of Competency only enrolment by first ensuring that nothing is selected on the first page of the Enrolment wizard, in the following area:
This is not a mandatory field, and will immediately ensure the enrolment recognises it is not to be associated with a Full Course or Qualification.
On the second page, you can select your Unit as you intend to use:
On the next page, you can then see that the Enrolment has automatically configured itself to be a Unit of Competency only Enrolment.
You can then fill out your details as you normally would (Such as Delivery Type, Funding Source, Concession, etc) with the confidence that this Enrolment is configured correctly for a Unit or Module only enrolment.