Hi David
I have created a simple Sandbox Solution that contains a Webpart to acitvate Features by entering the GUID. You can upload this solution, add the Webpart and then activate the Feature "73ef14b1-13a9-416b-a9b5-ececa2b0604c" - TaxonomyFieldAdded
Here is the URL to download the Solution: reallifesharepoint.com/.../office365-managed-metadata-the-required-feature-is-not-enabled-for-this-column-type
Cheers Simon