Integration at SQL level

I’ve developed an Interface between Nav 5.0 SP1 and a Logistic Software. Both BD are SQL. There’s a web service which calls Stored Procedures. Everything is working fine. My problem: I’ve got to rebuild the entire solution for a customer that doesn’t want IIS, web service, etc. Shorty: everything must be developed at SQL level. What is the best way to achieve this? ADO connection, ODBC. I’d like to use the Stored Procedures I’ve developed, to save time. Any advice? Thanks.