OK I recreated the problem. I got the error:
Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'XXXX'@'localhost' (using password: YES) in /tmp/cpanel_phpengine.1339860745.18344GCUcxSePgA on line 1617 Access denied for user 'XXXX'@'localhost' (using password: YES)
A quick Google search revealed that the issue is with a mismatched password in mysql. To fix this match the password for the mysql user with the cpanel password.
To resolve the issue simply log into your cPanel interface click on change pass and reset the password, relog into your cPanel interface and you should be able to access the broken features.
(For more info http://forums.cpanel.net/f5/fantastico- ... 71162.html
Which is what I did and it now works, SMF successfully installed. Your new cPanel password is on it's way to you via txt.