As far as I remember 6.5 does have SQL-DMO (SQL Direct Managment Objects).
This is like an object oriented api into SQL Server that you you can use from VFP using CreateObject("SQLDMO.Database") - See SQL Books onLine.

Failing this I know there was a C level API that you could code to.
Sorry this is all I can remember as I have long since turffed my SQL 6.5 Documentation.