Yup....LECOM made Step 1 a requirement a couple of years ago as well. I think more and more schools will in the future as it seems more residencies are asking for it from DO applicants. I can tell you that a significant quantity of EM programs want Step 1 and Step 2 and don't even care about COMLEX scores. In fact, with Step 1 going pass/fail, Step 2 will be even more important in the future and having the results BEFORE ERAS OPENS could mean the difference between getting 3 interviews and 18.
IIRC you need to have your school authorize you to take USMLE so contact your school's registrar's office and ask. Since your school isn't requiring it, you'll have to pay out of pocket....since LECOM made it mandatory, the cost was rolled into our tuition so the federal loans we were awarded had the Step 1 money rolled in.
Do yourself a favor and don't just use COMBANK/TrueLearn to study for Step 1.....get a Uworld subscription and hit it hard until you take the test....ideally you want to go through it twice prior to test day.