If you have to load package require XOTcl to your config file, this indicates that you have not installed xotcl properly.
In particular, after "make" in the xotcl directory, you have to use "make install-aol" to install xotcl.tcl and the xotcl serializer properly. For more details, see:
https://openacs.org/xowiki/xotcl-coreTriggered by your message, i extended the xotcl-core regression test (under automated test, <yoursite>/test) to check for the serializer as well. When your site is running the regression test properly, the basic installation should be ok.
Concerning installation of libthread, see e.g. https://openacs.org/xowiki/xotcl-request-monitor
-gustaf neumann