[root@machine ~]# yum --installroot=/data/xchg-2.0/ install apache2
[root@machine ~]# rpm --import /usr/share/rhn/RPM-GPG-KEY-fedora [root@machine ~]# rpm --import /usr/share/rhn/RPM-GPG-KEY [root@machine ~]# rpm --import /usr/share/doc/centos-release-4/RPM-GPG-KEY [root@machine ~]# rpm --import /usr/share/doc/centos-release-4/RPM-GPG-KEY-centos4
rpm also has a root parameter: $ rpm --help | grep root -r, --root=ROOT use ROOT as top level directory (default: "/")
so you'd want to use "rpm -r /data/xchg-2.0/ --import ..."
however, you'll also need to install of apache's dependcies in this chroot directory, probably not exactly what you want...
you might also want to look at rpm's --prefix=<dir> relocate the package to <dir>, if relocatable parameter (though I've never used it).
Cheers, MaZe.