Hi Gustaf,
Okay, I have to admit that I failed to compile mkZipLib due to my lack of knowledge of C compilers.
Here is the command I used to compile mkZiplib10:
gcc -DUSE_TCL_STUBS=1 -I/usr/local/aolserver45/include -I/usr/local/src/aolserver45/tcl8.4.17/generic -I/usr/local/src/aolserver45/tcl8.4.17/unix -L/usr/local/src/aolserver45/tcl8.4.17/unix -ltclstub8.4 -ltcl8.4 -lz -o mkZiplib10.so mkZiplib10.c zip.c unzip.c
It fails with /usr/lib/gcc/i486-linux-gnu/4.0.3/../../../../lib/crt1.o: In function `_start':../sysdeps/i386/elf/start.S:115: undefined reference to `main'
If I don't use TCL_STUBS it compiles, but I have no idea how I can load the resulting .so file. Although it is off topic, I hope you can give me a hand.