How to add minecraft.jar mods to the given modpacks?

[NarutoSasukeRasen]

I want to add a few minecraft.jar mods but I'm afraid if I do that then one of the mods will be broken so how do I add minecraft.jar mods without crashing? Please help me, thanks! :)

[freakachu]

simple answer: you don't.

complicated answer: you decompile minecraft with MCP, merge the changes made by forge and the other jar mods together, then recompile and replace the modpack.jar with the new jar you've created. if you have no idea what I just said, see the simple answer.