I suspect that you're overthinking things a bit, I don't really know that the Sarissa is enough different form a longspear to really justify different stats.
Also note that the macedonians were initially
a) professional soldiers while most of their opposition were militia
b) using the sarissa blocks as a defensive option and using cavalry to do most of the damage.
when they stopped using the sarissas as part of a combined arms approach they became less effective (tough to keep the formation together in a charge and open to being flanked)
c) really exposed vs fireballs in close formation...
based on wikipedia it seems like the shields are probably bucklers & buckler mastery might be the go for them.
Teamwork feats might be the way to go
Escape Route, Paired Opportunists, Shield Wall look reasonable options
Paired Opportunist would certainly represent the problems of approaching a formation (although the lack of facing in pathfinder also obscures some of the issues with formations only really being effecive in 1 direction at a time -> although the pikemen in napoleonic times did a big better against cavalry bit the cavalry was armed much differently with sabres typically)