You inspired/challenged me to try it myself
You still never told me what you wanted to use that required 4.1 though...but I had fun, so its ok.
I think I have figured it out (mostly). You need to make a template fragment saved as
/etc/e-smith/templates-custom/etc/my.cnf/010oldpasswords
containing just the text:
old-passwords
This will make the mysql daemon start with support for older style passwords (as suggested on their website). After you do that run:
/sbin/e-smith/expand-template /etc/my.cnf
You also need to run /usr/bin/mysql_fix_privilege_tables --password=(76 character default ldap password). This is trickier than with the 4.0 upgrade because it will not run without specifying the password. The 76 character password can be found by installing the phpmyadmin contrib and looking in the file /opt/administration/phpmyadmin/config.inc.php
After those things are done, post-upgrade and reboot and you will have mysql 4.1.8.
There are some other notes on the Mysql page I quoted abouve such as needing updated DBD or DBI packages or something, but webmail still works and phpmyadmin works after doing this - no other testing done yet. I will work on that.
Just a note - it is normal that the mysql update changes collation of tables to latin_swedish from latin after the upgrade - don't ask me whay, but I read it on their website. I'll post some more detialed step by step instruction in a bit.
EDIT:More instructions here -
http://forums.contribs.org/index.php?topic=25414.0 - lets move discussion to that thread.