What is Windows 8.1 Native Plugin Path ?

I develop Windows Store 8.1 plugin , but I have to split dlls by CPU (ARM , x86 ) . What are dlls Path?
Plugins/Metro/x86 , Plugins/Metro/ARM does not work !

Unity version : Unity4.7.0f1

I changed dll to Any CPU , after that I got this error : “Don’t use this function in the constructor or field initializers, instead move initialization code to the Awake or Start function.”

If you set Solution Configuration to “Master” , you can get rid of this exception !