Ok, i find the solution, when u play with the vanilla launcher, you need to install the optifine in .minecraft/bin/minecraft.jar (after 1.6), well, in FTB launcher and others launchers, you need to navegate to the mod pack folder, in this case Direwolf20_1_5, there are a folder called inst mods, this folder saves all mods that you ususally put in minecraft.jar. for example, forge, optifine, etc.
summarizing all, the mods that you usually put in minecraft.jar, put in the inst mods folder
PD:
Sorry 4 the english