Continuing on with the Systemless Root experiment, XDA Senior Recognized Developer Chainfire's latest release for SuperSU Beta includes automated boot image patching at the time of installation.

This essentially eliminates the need to upload specific boot images for devices as the zip installer for SuperSU will install SuperSU in systemless mode on Android 6.0 and Touchwiz based on Android 5.1, and then patch the boot image.

Dev notes for this beta release are as follows:

The boot image patcher currently only supports gzip compressed ramdisks and the standard Android boot image format. Some devices do not use the standard format, and many custom kernels use a compression other than gzip. A backup is made (/data/stock_boot_.img.gz) of the original kernel before patching it.

... The script inside the ZIP usually contains a lot of specific docs, but for systemless I have not written that part yet. The sukernel tool that does a lot of the patching magic is very chatty, telling you exactly what it does and how. In TWRP you can see it's output with "adb shell cat /tmp/recovery.log" after installing the ZIP.

Installation instructions have a few steps this time around. Essentially, users migrating from normal SuperSU installations in the /system partition have to flash the stock system partition content before installing this. This is usually achieved by reflashing the stock ROM, but instructions may vary slightly per device. Users on a previous SuperSU systemless installation have to still flash the stock kernel before flashing the Beta zip. Chainfire assures that future updates for systemless root will be easier to carry out, so the steps are not very tedious for a one-time setup.

The dev has tested the beta on a fair number of devices, including Nexus devices on stock Android 6.0 Marshmallow as well as on CyanogenMod 13, and the Galaxy S6 on stock Touchwiz based on Android 5.1.1. You can try this out yourself, but as with every other thing found on XDA, make a backup before installing. If in doubt, we also recommend searching the thread or forums for compatibility or device-specific issues.

For downloads, please head on over to the forum post. The dev requests that discussions should happen over at the SuperSU Beta thread, so head on over there for general talk. Keep in mind this is experimental, and there will likely be bugs, so proceed at your own risk.