I have had somethign similar in the past.
I gave them a role in the course, without enrolling them, through Course -> Participants -> Enrol -> Other Users.
This way they can access the course through the direct link, once they have logged in, but they are not enrolled, and won't show in the participants list.
I don't know if they still generate entries in the course logs though.
I gave them a role in the course, without enrolling them, through Course -> Participants -> Enrol -> Other Users.
This way they can access the course through the direct link, once they have logged in, but they are not enrolled, and won't show in the participants list.
I don't know if they still generate entries in the course logs though.