Thanks Gustav
The following script works under FreeBSD 6.0 with tcl 8.4.11:
---
...
cd /usr/local/src
tar xzf /usr/distfiles/xotcl-1.3.9.tar.gz
cd /usr/local/src/xotcl-1.3.9
./configure --enable-threads --enable-symbols --prefix=/usr/local/aolserver \
--with-tcl=/usr/local/lib/tcl8.4 --with-tclinclude=/usr/local/include/tcl8.4/generic
gmake
gmake install-aol
