I need certain courses not covered in my undergraduate studies, can I take them at another institution?
I would still suggest you contact the admission director (one more time)! He is the one with the "right" and "only" answer you need to follow. All what we can do is share relevant experiences that may or may not be along the lines of your school's standard/system.  

Having said that, If I'm not mistaken, I think you can take the courses in other schools (as long as they are accredited and/or sister schools + cover a similar syllabus as the one your school has). As for a database, try to look through your school's graduate handbook or admission website.