Normal Overload Situation
The "normal" overload situation is an uncertain prospect. You tell the student to find a class in which the instructor will guarantee a seat and have them add that course when the term starts. You fill out an online overload approval form linked directly from this page.
That "normal" case usually means adding a sixth class. I really like a student to have fives courses to give them options during the college's "course withdrawal period" (through 8/9th week get WN, WP, WF on the transcript.) So, if the student's selected five courses total over 17 credits (18 for seniors), you should write an e-mail to email@example.com specifying that fact. I don't know if this will work, but I think we should test it to exhaustion.
I'd really like my advisee to start with 5 courses to ensure (s)he has adequate leeway under the college's "course withdrawal period." The 5 courses that (s)he seeks for the fall total 18 credits. Could you please allow NAME ID to register for 18 credits now, instead of waiting for fall, to make this possible?
your name here
If that doesn't work, revert to the normal case.