How Are MS Customers Bridging The Parameter Gap When Calling Sqlclr Sps From External Ado Apps?

we've seen the ease of calling sqlclr stored procedures whose parameters are known sql data types but are wondering what we're in for when we wish to pass .net objects to a sqlclr stored proc. We're confident that the sp's external assembly itself would build if instructed to "receive" .net objects etc, but can't envision how/if the sp's signature would generate nor can we imagine how such an sp would be called. We're not even sure we can envision how another sqlclr object (eg a trigger) would pass .net objects to the sp. Are we faced with using user defined data types if we need to pass .net objects to such sp's?