This isn't a problem
For example, if your Teamcenter data model includes a new item type called CM5_MyItemRevision which has custom properties cm5_Property1 and cm5_Property2, then you merely need to define a Mendix domain model to contain this information, like so:
Then when you retrieve data from Teamcenter, apply the business object mapping to your domain model rather than the OOTB TcConnector model: