Once you get et2c and
et2c appmain.c >temp.c cc -c temp.c -o appmain.o et2c appaux.c >temp.c cc -c temp.c -o appaux.o cc appmain.o appaux.o et.o -ltk -ltcl -lX11 -lm
If you're using a Makefile, you might want to redefine the default rule for converting C source code into object code to incorporate the et2c preprocessor step. Like this:
.c.o: et2c $<>temp.c cc -c -o $@ temp.cThe et2c does not harm files that don't use ET constructs, so this rule will work for every file in your project.