If you want to install without modifying
/system then it's impossible. So the answer is "No, you can't" with neither root access nor recovery flashing. But if you simply wany to DIY without using a custom recovery, it's OK.
Takine OpenGApps as example. Download their ZIP and extract it.
- Install BusyBox
busybox lunzip to extract the
.tar.lz files in
- Move files other than APKs to
/system. You will find things to be merges into
framework/. Take care of file mode (permissions) and owner/group.
GoogleServicesFramework.apk as system app. In my experiments it sometimes fail if not installed as system app.
- Install the rest of the APKs as normal.
You can't install GApps without modifying
/system. As you see, there are quite a few configuration files that will be merged into
/system/etc during installation, and a few essential framework JARs to be installed to
'/system/framework. They won't work if installed elsewhere.