i learned in #gentoo-server that you can modulate whether or not distcc is used with the FEATURES option. the docs on gentoo.org tell you to put distcc in the front of the path so that calling "gcc" will always use distcc though.
The point is, the HOWTO should mention that you don't have to modify the PATH to make portage use distcc, just set the FEATURES correctly.
Steps to Reproduce:
The section which deals with PATH modification is to set up automake, not Portage.