There is no support for servers, please use Bukkit.
Any operating system that supports Java 1.7+
Easy download of patches
Additional instructions for manual way:
1. Download the Patches.zip here.
2. Choose your patch, each patch file will be named 'minecraft.patch' and will be placed in folders, the first letter of each folder represents the type of Minecraft revision (a = alpha, b = beta, f = full/final).
3. Copy the 'minecraft.patch' file to the same directory as MC Downgrader is located.
4. Run MC Downgrader and just click patch.
The download can be found here.
Choose which patch you want from here.
This tool is hosted by me. I am paying for the server fees out of my own pocket. As a student, it is extremely hard to come by spare money to keep this tool alive. So, please consider donating.
I share the same viewpoint as CyborgDragon.
This modifies the minecraft.jar binary file. By downloading and using this tool you understand the risks of damaging your minecraft.jar file and that 68x will not be held accountable for your actions!