Hi @TomPesach,
I believe the only really supported way of including Javascript/CSS in Canvas is through the Theme Editor, which is something your Canvas administrative team (usually located in the IT / eLearning / Digital Education areas) would need to do for you and would affect all courses in a particular account/subaccount. On that note, I am a Canvas admin for a higher-ed institution, and I can tell you that we are very hesitant to add code to the the global javascript files. It may be different at your school/institution, but the work required to maintain the files and the risks if they break are pretty big barriers.
Hope this helps answer your question a bit, even if it's not the answer you were hoping for.
-Chris
