In what sense do you want to change the ores? So that IC2 Ores generate during world generation instead of TE ores? This can be done in the config files, if you check the IC2 one and the TE one. If you mean changing the ingots, then this can be done using an item called the Forge Lexicon, just place in the ingot you want to swap, say a TE copper ingot and you can get out any other mod's copper ingot.