Downgrading autoconf/automake

What caveats should I know with downgrading autoconf/automake? The port to cmake is a wise long-term strategy but will take time. While svn remains in a mixed autotools and cmake environment, both sets of build tools are needed during the transition. As I am already two releases behind, I was thinking about moving to the next release of Slackware, which is now in RC status. That move also will allow me to test Trinity in an environment with KDE4 installed. That upcoming Slackware release comes with autoconf-2.68 and automake-1.11.1. As explained to me, I cannot build KDE 3.5.10 or Trinity with that version of those tools. I was thinking about updating to the new Slackware release and then temporarily downgrading to autoconf-2.63 and automake-1.10.1 so I can build and help test Trinity during the long-term port to cmake. I presume that if I want to build third-party packages for the new Slackware release, I might have to toggle to autoconf-2.68 and automake-1.11.1 to ensure no compatibility problems. Perhaps I need only downgrade autoconf and not automake. I have no clue if that is possible too. Will this work? Darrell