How to reference a non-COM dll without using DllImport attribute

Is there a way to reference a non-COM dll without using the [DllImport("dllname.dll")] syntax?  I was thinking you could add a reference to a dll and it would essentially create it's own namespace.  Instead, I get an error about the dll not being COM compliant.  The DllImport is fine for smaller dlls.  But if you want to add a dll that contains hundreds of functions, the code becomes pretty bulky and time consuming to create.