MassFX concave generation

Hi, i m using this to add massFX modifier to a selection of objects
for i in $ do (
addModifier i (MassFX_RBody ()) ui:on
i.modifiers[#MassFX_Rigid_Body].density = 9
i.modifiers[#MassFX_Rigid_Body].staticFriction = 0.5
i.modifiers[#MassFX_Rigid_Body].dynamicFriction = 0.2
i.modifiers[#MassFX_Rigid_Body].bounciness = 0.4
i.modifiers[#MassFX_Rigid_Body].meshType = 7
i.modifiers[#MassFX_Rigid_Body].compositeHighQuality = on
i.modifiers[#MassFX_Rigid_Body].sleepAtStart = on
)

but also want the modifier to generate the concave mesh for per object which is something i can't make work, I'd appreciate any help , thanks in advance guys.