Insert GUID using SQL Server Destination

Need to be able to insert GUID using SQL Server Destination. Common scenario: have a batch (header) table and a detail table for an ETL process. Using a stored procedure to create a new batch record, which returns the new row id (uniqueidentifier) of the batch record. SSIS doesn't support GUIDs at the variable or parameter level, so we return this as a string (bad practice already?). Now, we need to insert this value for each record going into the detail table, which is performed using a SQL Server destination operation.

Any ideas?

JB