Hi!! I recieved a few cuttings from various plants today,one of them being a viburnum, and was trying to find ways of rooting them when I stumbled accross this forum and this thread. I read your question and thought someone had an answer other than to tell you to "go buy some". Well thats just no fun for someone like me who enjoys the challenge of trying to get free stuff! SOOO I searched and found a site that might be of use to you. I had to register here just so I could share it so I hope it's of some use to you. It has ways to root cuttings from all typs of flowering shrubs including viburnum. Here's the link http://www.ces.ncsu.edu/depts/hort/hil/hil-8702.html.
Happy rooting
Sharon