In Impromptu, before you open the catalog, select Tools--> Options.
Uncheck "Retrieve database tables when editing catalog tables"
Open the catalog. Select Catalog-->Tables.
There will now be a "Retrieve Tables" button below the Database Tables listbox. Click the button and select the database objects you want to see (check views in the User column).
Click Retrieve and add the view to your catalog.
HTH,
Justin