You are sure? strange, i have just now downloaded xotcl-1.5.3.tar.gz and it is ok (downloaded via FF from the link above). For reference the downloaded file:
-rw-r--r--@ 1 neumann 501 1961146 17 Jan 20:54 /Users/neumann/Desktop/xotcl-1.5.3.tar.gz
MD5 (/Users/neumann/Desktop/xotcl-1.5.3.tar.gz) = ed246596550812375ff4461c07b89bcb
Anyhow, you should use 1.5.6 from http://media.wu-wien.ac.at/download.html
