Disable the public key check for rpm installation

I want to make a DVD with some useful packages (for example php-common). The only problem is that if I try to install on a computer that's not connected to internet, I can't validate the public key.

The scenario is like this:

1. I download the RPMs, I copy them to DVD.
2. I install CentOS 5.5 on my laptop (it has no internet connection).
3. I try install one using yum (or rpm -i, or whatever).

I get the following error: public key for "package" is not installed.

How can I bypass that?

From yum -h:

--nogpgcheck          disable gpg signature checking

If you want to disable the GPG validation for the whole Repo, add the following line to the Repo definition in /etc/yum.conf:

gpgcheck=0

If you are installing local RPMs using yum, do as Ignacio says.