The Traditional NI-DAQ ActiveX controls are included with NI-DAQ 7. To install them, you need to select "Measurement Studio ActiveX Controls" which is located in the feature tree under "Microsoft Visual Basic Support" in the installer. This is the easiest way to use Traditional NI-DAQ in .NET.
National Instruments does not currently supply a class of P/Invoke wrappers for Traditional NI-DAQ. There are some examples available like
this one that contain wrappers for a few Traditional NI-DAQ methods and show how you would create the wrappers for the functions you need.
I hope this helps.
Good luck with your project.
Tony H.
Measurement Studio