Success!!!
After mining (get it through the source code for half a day (not to be provd of I at last came up with a method which does what you want (and so do I).
!WARNING!
This is a code which was a result of a half a day of reading through the internet so it's not writen well. Also... if you can rewrite in a better state then do that and post it here please. So here goes:
I think I also have some explaining to do
1. This goes in the mod_xxx.java
2. For loop loops through the slots in the current inventory (crafting table/inventory crafting space) looking for the item stated in the if statement
3. Now this is the stupid part but I couldn't find a better way... The truth is that takenFromCrafting is called before the ingredients are destroied or at least that is what I've found (Lex?) that is why you have to make an ItemStack of two Items so that one is destroied and the other stays in the grid
4. this in the if statement is the BaseMod class or the class having your item defined in
5. Then is just the damage calculation depending on the ingredient (Item)
This is it If you have some more questions be sure to ask and I'll respond asap.
Have fun, JKK.
EDIT: Eloraam if you see this, would you mind not die because of laughing Maybe even supply us with your code? (not begging ofc)