The two main domains following the Google instruction for blogger/blogspot sites.
-www.error418.fr for the french version of the blog
-www.error418.org for the english version.
In fact, I had to be patient and wait for the DNS propagation. You can track the propagation with some sites like http://www.whatsmydns.net/
Reducing the TTL may be an good idea, but you must do it the night before the change to be sure it is active.
The domain 418error.net is redirected to error418.org, with an .htaccess file 301 redirection.
RewriteRule (.*) http://www.error418.org [R=301,L]
Other forms of redirection may be penalized by the Google search engine, which could be considered as "duplicate content".
To do the expriment I redirected www.error418.net with the simple redirection interface of my registar.
The www.htcpcp.net, domain will be used for my teapot, with an simple 'A' record.