Custom Fields in BOPF model UI

Hello all.

I know I can extend the metamodel and database tables but is it possible to add custom fields to the BOPF modeling UI itself? Either in Sapgui or eclipse.

I would like to create a model which fetches data from customizable criteria and the most logical would be to add these criteria to the metamodel directly. However, then I would need to access these fields also from the UI.

Thanks a lot.

Martin Jonsson