I just let people with a pointy-stick ready vs. approach and if the approach is via charge, they get the setting damage.
And yet, honestly, that's never ever ever happened in any game I've been in or run, even being fast and loose with the rules. It's a cold day in the hot pits when somebody actually picks up a spear of any sort, as well.
If anything, I think the maneuver should be encouraged, just to encourage variety in weapons. If it's utterly impossible to set vs charge, why not just grab a glaive for more damage?
It might only, normally, play hell against zombies ... unfortunately the average damage of a Str10 guy weilding a spear set vs. charge is about 9 and zombies have DR 5/Slashing ... >.< So it isn't even all that great for arming the peasant milita to stop that advance by the zombie hordes.
--fje