[CentOS] Setting up a chroot

I'm trying to build GNOME (to run a more recent version than 2.16.* on
CentOS 5.1) and I keep running into a lot of rather strange problems.

I'm wondering if this might have something to do with my hybrid 64 and
32 bit general environment, so I want to try a pure 64-bit chroot.

I've never done this before, and I'm not entirely sure how to, and I
didn't see anything particularly on point, either at centos.org or
google.  If I missed it, just say where and that should be enough.

Guidelines?  Suggestions (other than "go away" or other physically
difficult crudities :-)?

Thanks.

mhr