Using fakeroot and fakechroot, it is possible to setup and use a chroot environemnt without ever becoming root. The following will build a new installation in chroot/ and after installation will switch into that installation (do all this as non-root):
$ PATH=/usr/local/sbin:/usr/sbin:/sbin:$PATH HOME=/ LOGNAME=root \
fakeroot -s chroot.save fakechroot \
debootstrap --variant=fakechroot etch chroot/ http://ftp2.de.debian.org/debian
$ PATH=/usr/local/sbin:/usr/sbin:/sbin:$PATH HOME=/ LOGNAME=root \
fakeroot -i chroot.save fakechroot chroot chroot/ /bin/bash