Verified answer

Industrialcraft is not installed in the jar. industrialcraft is installed in the mods folder. Here is the link to my 1.8.1 jar with everything you need to use industrialcraft, toomanyitems, and optifine:

http://dl.dropbox.com/u/2813860/minecraft.jar

Here is the link to the file you need to put in your mods folder in the .minecraft folder:

http://dl.dropbox.com/u/2813860/industrialcraft-2-...

Cheers,

Keanu