I just stumbled on this today. According to the DBCC CheckDB documentation, as of SQL Server 2014 Service Pack 2 you can now specify MAXDOP when running DBCC CheckDB! The documentation states:
Applies to: SQL Server 2014 SP2 through current version.
Overrides the max degree of parallelism configuration option of sp_configure for the statement.
Awesome! I’m not sure how this flew under the radar, it doesn’t even appear to be listed in the release notes, but I’m glad it’s there!