Change into the INT2LM source code directory:

cd /$TSDIR/src/int2lm

Open the Fopts script with any text editor and change the fortran options according to your computer platform. Compile INT2LM:

make

If compilation is successful an executable $TSDIR/src/int2lm/bin/int2lm.exe is created.
If gmake is installed on your computing system you may try to perform a parallel make by typing:

gmake -j N

this results in a much faster compilation. Replace N by the number of requested processors.