For optifine:
Download correct version.
start FTB launcher
Select modpack you want to use
click Edit Mod Pack
(this part is what i used, not sure if its the best way)
click jar mods
click open folder
Copy optifine to folder
close Mod Pack Editor
Launch Mod Pack
 
You'll have to do this every time they do pack update.
				
			Download correct version.
start FTB launcher
Select modpack you want to use
click Edit Mod Pack
(this part is what i used, not sure if its the best way)
click jar mods
click open folder
Copy optifine to folder
close Mod Pack Editor
Launch Mod Pack
You'll have to do this every time they do pack update.
 
				
		
 As long as players enjoy the pack now, and want to see it in the launcher, they will add it
 As long as players enjoy the pack now, and want to see it in the launcher, they will add it