you could use winRAR and place each item sepratly or you could use mod tools but that can only put in mods that only need to put files into the minecraft jar and nothing else (so nothing like mo creatures or mo creeps and wierdo's etc. but you can do stuff like better than wolves single player commands zombes mod pack and too mant items etc.)
mod tools download link: http://www.planetminecraft.com/mod/mod-tools---install-mods-with-ease/
