Material mappings for bullet strike

When a bullet strikes metal it should throw sparks and go 'ding', when a bullet strikes dirt it should throw up a bit of dust and go 'thwop', and so on for different materials.

What I need to do is associated different textures with different particle emitters and sounds so that I can create different effects and sounds for bullets striking different materials. This is similar to addMaterialMapping for foot fall sounds/puffs.

This would probably require knowing which texture was struck (for DIFs) and what obj datablock (for DTS)

Can anyone suggest a way to achieve this (preferably in script)?