Lian Wan Situ - 2011-11-30

If you are running the Ubuntu(possibly Debian as well) patched version of xchat you need http://lwsitu.com/xchat/cap_sasl_xchat.pl which includes a workaround for problems caused by the patches instead of the plugin mentioned in that post.

Usage is a bit different:
/sasl set <net> <user> <passord> PLAIN
/sasl save

<net> should be the name you have for FreeNode in the Network List (ctrl+s)