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NOTE: Information extracted from internet, not mine.
Minecraft Coder Pack Set Up for 1.2.5 and Up, Part 1 of 3, By Fyoface
How to mod minecraft forge mods
This will help you with all your needs
I'll show you, what is needed to install the High-D Texture Pack (all versions).
This is an easy way i use to install a minecraft mod such as "Toomanyitems" for windows.
(You will need WinRAR or 7-Zip, i believe they are free)