The problem I had was that the installer was set to update the database details in wp-config.php
according to the install script it should:
Code:
rename("$installdir/wp-config-sample.php"," $installdir/wp-config.php");
But it didn't 
So as wp-config.php is named in the tarball as wp-config-sample.php I had to go to:
/usr/local/cpanel/addons/WordPress
then open pkg.tar.gz
rename wp-config-sample.php to wp-config.php
Zip it and tar it up again then run the installer which worked fine, I suspect it will be overwritten with the next cpanel update though *shrug.