Installation instructions:

For general instructions to install a mod, read this:
http://www.minecraftwiki.net/wiki/Mods/Installing_Mods

This mod requires ModLoader. Download and install before installing this one. You can get that here:
http://www.minecraftforum.net/topic/75440-v145-risugamis-mods-updated/

Once you have ModLoader installed, do this:

Windows ME/95/98/XP:
1.Click start.
2.Click Run....
3.Type %AppData%.
4.Open .minecraft.
5.Open bin and you will see minecraft.jar (It may appear only as minecraft)..
6.Open the folder using an archive software (the most popular are 7zip and WinRar). To do this, right-click minecraft.jar and hover to the Open With menu.
7.Open the Mithril.zip file, using the same archiving software.
8.Copy the class files from Mithril.zip into this folder. Copy the Mithril folder from Mithril.zip into this same folder.
9.Open the subfolder "armor". In Mithril.zip, open the Mithril folder. Copy 4 files from Mithril to armour: bronze_1.png, bronse_2.png, mithril_1.png, mithril_2.png
10.Exit the folders.

Windows Vista/7:
1.Click the Start Icon.
2.In the Search Bar, type %AppData% and press Enter.
3.Open Roaming.
4.Open .minecraft.
5.Open bin and you will see minecraft.jar (It may appear only as minecraft).
6.Open the folder using an archive software (the most popular are 7zip and WinRar). To do this, right-click on minecraft.jar (note- if you don't have winzip,7rar.etc., go to control panel and find folder options, view and uncheck hide extensions for known file types. go back to minecraft.jar and rename it "minecraft.zip".don't forget to change the name back to minecraft.jar when you're done!) and hover to the Open With menu.
7.Open the Mithril.zip file, using the same archiving software.
8.Copy the class files from Mithril.zip into this folder. Copy the mithril folder from Mithril.zip into this same folder.
9.Open the subfolder "armor". In Mithril.zip, open the mithril folder. Copy 4 files from mithril to armour: bronze_1.png, bronse_2.png, mithril_1.png, mithril_2.png
10.Exit the folders.

Macintosh:
1.Click Finder.
2.From menu, choose Go, Go to Folder.
3.Enter "~/Library/Application Support/minecraft/"
4.Open "bin"
5.Install decompression software. (The Unarchiver on the app store)
6.Decompress mincraft.jar file
7.Put the parts of the mod into the folder (see steps 8 and 9 from Windows).
8.Exit file and add extension .jar to the name