[WP 8.1] Interop - Extra e info problem

Hello everyone,
I'm trying to do some registry changes in my Lumia 640 LTE, and so I need to do an interop unlock. I've followed steps from

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http://forum.xda-developers.com/windows-phone-8/development/xap-customwpsystem-patch-xaps-wpsystem-t2975419

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and got stuck on installing Extras e info on SD card - Store says that the publisher doesn't allow to install it on SD card, so it's impossible to do the rest of the guide. I also tried to replace Preview for Developers, but after finishing, opening isn't possible, it just run for like 0.5 sec and then exit. Can anybody help me with this problem? My target is to reach registry files to add custom theme colours and change transparency of apps pinned on desktop, as it is in WP 10 (which I don't want to use due to problems with stability and SD card). I tried other SD card, rebooting, reinstalling everything. Software is fresh, I did rollback fro WP10 today. Help!

PS. Sorry for misstakes, I have to Polish my english and I know that.