How to get the exact hit position in Minecraft Forge/MCP?

I am working on a project for Minecraft. I want to figure out exactly where a player was hit. For example, I want to be able to display a particle effect exactly where the player was hit (like chest position, left arm position, etc). The class Minecraft(accessed through Minecraft.getMinecraft()), has a variable called objectMouseOver. This variable has a field called entityHit which is what your looking at. Unfortunately, this does not tell you exactly which part of the entity is being looked at.

Can someone help me figure out how to get the exact position that is being hit/looked at? Any answer in Forge or MCP will be very helpful to me.

Thank you!