Hi, James! I have not tried this -- hopefully others who have will chime in -- but I did find
this page on growing blue elderberries, which says, "Propagation: Usually by cuttings, also seed," and "Planting: Place rooted cuttings and seedlings, that are at least one year old, in full sun in well draining soil." It seems to me that it's worth a try, especially if you have a good rooting hormone like willow
water to help out, following something like
these guidelines. Please let us know how it goes!