How do I keep emerge kdebase from looking for the internet but instead /gentoo/usr/portage/distfiles/?
You could probably change /etc/make.conf to:
PORTDIR=/gentoo/usr/portage DISTDIR=${PORTDIR}/distfiles
But after the install is done you will probably want to change it back to:
PORTDIR=/usr/portage DISTDIR=${PORTDIR}/distfiles
Hope this helps some.