You should use the ANSI C API to call NI-DAQmx with Borland Builder C++. For more information, see the DAQ Quick Start Guide, the NI-DAQmx Help, and the NI-DAQmx C Reference Help under Start>>Programs>>National Instruments>>NI-DAQ.
I have the same problem as Fabrizio ! I can run properly the DAQmx ANSI C functions with VC++ but I can't use them with Borland because of a compliance problem. So I tryed to use the Coff2omf software to create a correct ".lib" file ...
If the tools that Borland provides for converting import libraries don't work for the the DAQmx import libraries, I think your only option will be to link explicitly to the DLL through LoadLibrary and GetProcAddress.