Board Thread:Questions and Answers/@comment-83.40.230.105-20130409085856/@comment-13413401-20130728023306

You can add any mods to the mods folder as long as they are for Minecraft version 1.4.7 and the new mods do not conflict with other mods.

However, I'm not sure if it is permitted to modify the tekkit lite package... With all the copyright laws, I don't think that users are actually allowed to modify it (even though everyone does it).

In fact, if you look in the bin folder, you will see that there is a .jar file called modpack.jar in addition to minecraft.jar. Normally, when modding minecraft, users just copy the mods or an API like Forge into to minecraft.jar file. However, the creaters of tekkit lite do not have permission to actually modify that file and distribute it, so they added a new file called modpack.jar. Instead of "modding" minecraft.jar, they added Forge and other things to modpack.jar...

SOURCE: Technic platform, making your own modpack -->  http://www.technicpack.net/article/view/building-your-own-modpack.7

Quote from the website:

"The general rule is to install the mod in this area exactly how the mod author describes on their site.  If a mod is listed as a core mod, create and place it in a 'coremod' folder.  Mods go in a 'mods' folder, and any config files you've created go in the 'configs' folder.  The only exception to this is if a mod has files that need to be placed inside minecraft.jar.  As you should never redistribute minecraft as per the Terms of Use, you will instead place all of these files inside a 'modpack.jar' you create yourself.   A Jar is simply a zip archive recognized by java, so creation of the jar is as simple as renaming a zip as jar.  Any archive program can be used to do this as long as the extensions saved as are .zip. Below is a demonstration on the steps used with WinRAR."

So I'm not sure if we (the users/gameplayers/modders) are permitted to change tekkit lite, even if we do not distribute our version... Any comments?