Gustaf,
It is very strange! The only way i could have libthread2.6 compiled with Ns_ModuleInit was changing by hand generic/aolstub.cpp to
/* #ifdef NS_AOLSERVER */
#include "/usr/local/aolserver/include/ns.h"
althroug my CONFIG was passing parameter "--with-aolserver" the var NS_AOLSERVER was not setting. I do not know why.
This way i could have as a result from "nm libthread2.6.so|grep Module":
00001654 T Ns_ModuleInit
00011b6c D Ns_ModuleVersion
and libthread2.6.so module was loaded correct by aolserver when declaring "ns_param libthread            ${homedir}/lib/thread2.6/libthread2.6.so" in modules section.
Problem now is with throttleThread 😟
When I put your modules/tcl/*xotcl files in my aolserver dir modules/tcl/ and reload aolserver thats ok. Server is up but every page i browse nothing happens and this message is written in aolserver log errors:
"throttleThread do ::throttle check 200.181.95.53 200.181.95.53"
    ("eval" body line 1)
    invoked from within
"eval [my server] do [self] $args"
    (procedure "do" line 3)
    ::throttle ::THREAD::Client->do
    invoked from within
"my do check $requestor $pa"
    (procedure "check" line 11)
    ::throttle->check
    invoked from within
"my check"
    (procedure "postauth" line 4)
    ::throttle->postauth
    invoked from within
"throttle postauth"
(xotcl 1.3.4 is installed with make-aol; xotcl.tcl is in $aoldir/modules/tcl/ and *xotcl files are sourced because when i remove them the website pages display fine without any error):
Maybe errors in throttle_mod.xotcl script (as Malte observed)?
Thank you for your patience.