There is no specific functionality for consignment and there really is no requirement for anything other than what is already present.
The only difference is from a reporting perspective and the easy way is to do this with the standard reports is to select the most appropriate field available from the report criteria (e.g., Manufacturer, Category) so that you can limit the reporting as required. If you select a value or values at the end of the range of used values (e.g., ZZCONSIGNMENT VEN1), your process is simplified greatly.
The route that I would select is to go with custom reports and possibly modified standard reports as that allows you add a new custom field to indicate a consignment stock code. More work to start with, but it allows you to only differentiate between consignment and regular inventory only where necessary.