I'm glad you found the article useful to you! Every college has its own unique policy about CLEP exams, and some colleges give a grade that affects GPA and other's give credit but not grade, and others don't give credit but do give placement into upper level classes. 3 of the schools we applied for provided CLEP credits, but none of them gave a grade, so our GPA was not affected. I haven't read about many college giving an actual GRADE for a CLEP exams.
In contrast, AP exams usually do have a grade that is applied. Generally for an AP exam, a score of 5 (perfect) is an A, 4 is B, 3 is C, and less is not given college credit. I do know one homeschool student who took an AP exam and scored a respectable 4. She was disappointed, though, because that was the only "B" for her entire college career.You might want to check the colleges your student might apply for, and see what they have for their own unique policy.
I wish I could give you a more direct answer to your question, but each college makes up their own rules. I can suggest a website that provides some free lessons plans for CLEP study available online: clepprep.tripod.com. I hope that helps!