This is not maintained, although you may find it helpfull since the internet lacks information of how doing this stuff. I'm not even sure if it still working nowadays, although it has been confirmed by @WindSekirun around Apr 2016. If you're currently working on it and you can confirm it still works or/and if you had to do any adjustment in order to make it work I would be very happy to add your updates here. :)

Rich and detailed explanation of how the initial idea and the working code was originally created How to install an application in background on Android

Extra: Apk with system privileges

• Enable Gradle Build System instead of ADT
• Change Layout Position
• Up to SDK Version / min: 8 -> 15 / target: 8 -> 23

Tested on

• Galaxy S7 SM-G930S | for Korea Market | Exynos 8890, LRDDR 4GB, Marshmallow 6.0 APD1 runnning Kitkat 4.4.2

Just open a Pull Request, issues or even help to answer some. :)