Sorry - my terminology was a bit misleading (this whole realm is full of overloaded terms).
What I meant at the time was "insert each row into the db as a separate insert statement" - I hadn't really noticed the way your stored procedure was set up. So, just loop through all of the rows of your table, running the stored procedure call multiple times (and tag each column to insert as a separate stored procedure param). That's still going to be the simplest solution, by far.
If you absolutely have to get this done, your next simplest solution is going to be writing a custom module. Yes, really. Failing that, it's theoretically possible to get your own connection object to construct a stored procedure call yourself, but it's far from trivial - you'll need to get the root GatewayContext, then get the DatasourceManager, then create your own connection object to use.
Our design services department could definitely help you out with the latter two options, but, really, just modifying the procedure (or creating a new one) and calling it successively is by far the best option.