In PlayerMobile.cs starting around line 969, the resistance stuff starts with 'OnSkillInvalidated(Skill skill)' Method and end down around line 1187 with the last method 'GetMinResistance(ResistanceType type)'
You should be able to rework this section, mainly the 'GetMaxResistance(ResistanceType type)' and the 'ComputeResistances()' methods are what your after!