Hi Nikolaus,
well, there are ways, though they differ between the 32- and 64-bit versions.
As far as the 32-bit version is concerned (as in your case), you need
to write a glue function to call non-PicoLisp libraries. You can do that
either as a normal, separate shared object (.so), or with inline-C.
Examples for libraries are 'ext', 'ht' or 'z3d' in the PicoLisp release.
Examples for inline-C (via "lib/gcc.l") you can find in "lib/readline.l",
"rcsim/tone", "misc/fibo.l" or "misc/crc.l".
Is this what you were looking for?