Hi class, 
Our group is trying to do matching with a continuous treatment variable. We've tried to use MatchIt with cem and cem() itself but have failed to get matches. We've also tried to coarsen the treatment into categories, but the methods are still not working. We would ideally like to match groups that are at least two category levels apart out of 4 categories (i.e., 1 and 3; 2 and 4). If anyone knows anything about multicategory treatments for cem, which the documentation says it can do, please email me! 
Thanks,
Jackie