Beam eighth notes in pairs by default

[Christopher Meredith]

I know this is pretty simple, but I can't get it to work for the life of me. I want to cause eighth notes to be beamed in pairs by default, rather than fours. I use mostly 4/4 and 3/4 time. I found this:

http://kainhofer.com/~lilypond/ajax/user/lilypond/Beams.html#Setting-automatic-beam-behavior

But nothing directly addresses what I want to do, at least as far as I can tell. I tried adapting one of the examples that uses sixteenth notes, but was unable to achieve the desired results. Can anyone help? Thanks!