Compiling and linking are done using the commands of your C compiler. The example ship with make and workspace files for Microsoft C/C++ versions 4 (venext4.mak) and 6 (venext6.dsw and venext6.dsp). The example batch files batch file mscvxt32.bat are designed to compile and link the file using 32 bit Microsoft C compilers.
To compile and link you will need to include the files venext.c, venext.def. You can also link with vensim.lib, but it will work better if you do not and instead use the callbacks in VGV to access any Vensim functions. when linking with Vensim. If your linker will not work the vensim.lib file that ships with Vensim you will need to create an exports library from vensim.def and vensim.c which contains shell versions of all the exported functions.