I can copy the sproc manually, so this isn't a terrible problem.
CREATE SYNONYM [dbo].[ExternalDocument] FOR [ExternalDocumentServer].[externalDocuments].[dbo].[tblUrl_blob]
When I try to sync with another db I get this error:
The following error message was returned from the SQL Server:
 Transaction context in use by another session.
The following SQL command (shortened by removing other attributes that get updated) caused the error:
ALTER PROCEDURE [dbo].[co_url_URL_Document_insert]
INSERT INTO dbo.ExternalDocument
The following messages were returned from the SQL Server:
 Altering [dbo].[co_url_URL_Document_insert]