#man authconfig
And you will see there is one option shown below:
--enablemkhomedir create home directories for users on their first login
Just use this option to create the home directory.
Odd, this option was not on my manpage. And it didn't work on one of
my servers. I have two CentOS 5 servers, but one is at revision 5.3,
the other running 5.1. The RPMs are:
authconfig-5.3.12-2.el5 - doesn't work
authconfig: error: no such option: --enablemkhomedir
authconfig-5.3.21-5.el5 - works fine!
Perhaps only very recent versions support this? The reason I ask is
that I have dozens of servers that will need this configuration, but
only some are running Red Hat or CentOS versions new enough to support
the command line option.