Sideloading apps unpublished apps possible?

I recently bought a treasure tag and had to see that the WP app is no longer published, meaning this useful piece of plastic is not usable for me right now. I was able to find the original app as .XAP and .APPX-BUNDLE but since that app was once published, it is now encrypted and can't be sideloaded without getting error messages.
Is there any way to get the app working again? I basically need a XAP deployment tool which is able to "pirate" these extensions so that I can use my treausre tag finally.
Is there any tool out there or did one of you maybe made a homebrew version of that app ?