NAV BizTalk Integration

I am trying to consume a BizTalk WCF service through Navision. In my current approach I have created a .NET DLL in which I have added a service reference of the BizTalk service. Navision consumes BizTalk Service through the DLL. Things are working fine by using .NET DLL. But as per new client requirement, the BizTalk service should be consumed directly by the Navision(Without .NET DLL ) because the client does not want DLL installation dependency on each and every machine. When .NET DLL is in the picture all proxy related things are handled by the DLL itself, but in case of Navision several lines of code required for BizTalk Service consumption. I have tried to do it by SOAP XML but got stuck in User Security Token. Is there any other way around to do this. Please help.