Pre-med courses through placement-credit tests??

Has anyone taken required courses [bio and chem] through placement tests? That is taking the test [for credit] without attending a course. Placement tests are offered for beginning [pre-requisite courses] through measurement and evaluation office. The letter grades appear on the transcript.
Do med schools accept such credits?
I have done a couple of physiology and physiology lab courses in grad school. I have already done lots of math, phy and chem classes. I was thinking of taking couple of beginning courses through placement just to meet the pre-requisite. I really want to avoid taking formal classes.

I don't have CLEP credit for any prereqs, but I noticed at least one of the schools I'm interested (Medical College of Wisconsin) specifically states that they don't accept such credits. So I'm going the classroom route.

I had CLEP English credits, but some schools said on their MSAR that this was not acceptable for the English prereq - so I took a full year of composition

Fonzy, you’ll have to go to schools themselves to get guidance on this question, and their answers may vary.
If I may play devil’s advocate for a minute here, the question I can imagine springing to the mind of an admissions person is, "You say you really want to go to medical school but you can’t figure out a way to take a few classes?"
Not saying I feel that way but you should anticipate that reaction.

Thanks everyone!
Mary, I appreciate your point. However, I have done two courses [including a lab.] at grad level, which could count as bio requirements. I just want to take two basic courses as placement because I do not want to spend money and time doing something which I can study on my own. I have been advised to work in a bio lab for six months as it will strengthen my credential. In my undergrad I have also done 'Plant Science and Micro-biology' But those courses are very old. Because of my engineering [and research] background I am used to doing work on my own. That is why I have asked about med school curriculum and life in a different thread. Also, my choice for specialty [radiology] is based upon my interest, background, and personality. I prefer not to sit thru' lecture classes.
I am also looking for info' regarding such med schools where emphasis is on self learning rather than long lecture hrs.
I am very glad that there are so many people here to inspire me and help me with my questions.
thanks and best