Actually, if the content of the course reflects a "BCPM" type course, then you can count it towards BCPM, I've been told.
For instance, I had an economics course that was called "intro to statistics." After asking my premed advisor, I was told to put it into the BCPM category, because it is there where statistics is classified (as a math). Hence, it is less about the department and more about the class content, and my AMCAS app seemed to go through fine (no x's for that class). I suppose this is the way the methodology for applicants to classify their BCPM classes tries to stop applicants from putting down (and fails, for students list it as BCPM anyways), for example a physics class that only focuses on history of physics and no physics,.
Just my two cents! 🙂
-Ice