Hi Glen, welcome to Gentoo. :)
The main worry I have is that if I try to emerge-sync I'll be inundated
with
1000's of updates and my poor ol' 28.8 connection will be tied up for a week. I've looked at the web site documentation, but there is no
suggestion
of using anything but portage for updates.
I know a few people who use Gentoo over dialup links. One on a 28.8k, and the other, a 56k.. so it can't be that much of a PITA doing updates. Anyhow, think of portage as you would rpm. It's the package management system, and trying to bypass one of those, is generally not a good idea. :)
I'm guessing that portage just adds a script to the sources (maybe a patch or two), but does anyone know if I can just download the script and patch then use the source that I already have?
Portage is the entire package management system. It knows what's where, why and what ever else it needs to. When you emerge sync, it simply updates your local portage tree (the ebuilds & patches) via rsync - which shouldn't take very long after the first sync.
If by "use the source that I already have", you mean a tarball that you've obtained via a source other than the internet, then just place it in /usr/portage/distfiles/ and then "emerge cat/app". It would have to be the exact same one that would have been downloaded though, otherwise MD5's wouldn't match (Can manually be worked around.. but different tarballs could cause problems later).
My advice would be to let portage handle itself and not to try to work around it.
All in all, I've been drinking, so don't expect anything very useful. :)
-- Wayne.