Platform Dependent library

I got different jars as well as dlls that they are platform specific so how can I tell unity3d to load each & attach for each platform. I know how to do it for the class level as noted there Unity - Manual: Conditional Compilation.

According to Special Folder Names on the wiki:

Plugins/x86
If you are building for 32-bit or a universal (both 32 and 64 bit) platform, and if this subfolder exists, any native plugin files in this folder will automatically be included in your build. If this folder does not exist, Unity will look for native plugins inside the parent Plugins folder instead.

Plugins/x86_64
If you are building for 64-bit or a universal (both 32 and 64 bit) platform, and if this subfolder exists, any native plugin files in this folder will automatically be included in your build. If this folder does not exist, Unity will look for native plugins inside the parent Plugins folder instead.

If you are making a universal build, it’s recommended you make both the x86 and x86_64 subfolders. Then have the 32-bit and 64-bit versions of your native plugins in the proper subfolder correspondingly.

Plugins/Android
Place here any Java .jar files you want included in your Android project, used for Java-based plugins. Any .so file (when having Android NDK-based plugins) will also be included. See Unity - Manual: Create and use plug-ins in Android

Plugins/iOS
A limited, simple way to automatically add (as symbolic links) any .a, .m, .mm, .c, or .cpp files into the generated Xcode project. See Unity - Manual: Building plug-ins for iOS
If you need more control how to automatically add files to the Xcode project, you should make use of the PostprocessBuildPlayer feature. Doing so does not require you to place such files in the Plugins/iOS folder. See Unity - Manual: Build Player Pipeline