emerge -f kde-cvs (for instance) does not use CVS to download the sources. Downloading occurs at the 'compile' stage. Reproducible: Always Steps to Reproduce: 1. 2. 3.
This is a fix I'd like to see as well. I live in a fairly rural area, and my only options are dialup, satelite, and nothing at all. Prefetching source is the only way I can maintain my sanity and still use Gentoo (it's helpful to start up a 'emerge -f whatever' session at night.) If you're working with the KDE cvs builds, you could always give cvsup a go, follow the official KDE instructions on grabbing the source by cvs, put the source in the proper place, and when you go to emerge the builds, set ECVS_SERVER to 'offline', which should disable fetching. Note that I've not tried this yet, so YMMV.
This isn't currently fixable due to a portage limitation which prevents overloading of the _fetch functions.
