I tried with the old debian tcl 8.4.0 binary package,
then I (IIRC) tried compiling it manually with threads, and that didn't work,
eventually I followed the openacs docs to the letter and configured,built and installed tcl 8.4.5 (using the link there) under the rather non-standard location described in the docs (under aolserver i believe).
it does work, once you find the magic combination. dont deviate from the docs and you might have more luck.