How to use the Grove-UART port for GPIO on BBG?

I see several examples on the web on how to use the Grove-UART port for GPIO. They talk about modifying a line in /boot/uEnv.txt:

For example, this page http://www.seeedstudio.com/recipe/index.php?controller=recipe&action=show&recipe_id=362&ref=product

…states in somewhat broken English:

Then blocking “cape_enable=capemgr.enable_partno=BB-UART2” just as the picture below shows.
#cape_enable=capemgr.enable_partno=BB-UART2

But looking in /boot/uEnv.txt, I’m not seeing this exact line to comment out. I’m running Robert Nelson’s Ubuntu 16.04 image.

There are hints that a better method exists to do what I want. References like this one from 10 months ago:

“Using cape-universal is a better way to enable UART2 these days, rather than forcing it in uEnv.txt. Most of the Python libraries know how to load the required cape overlay to enable UART2 and this should be checked.”

Can someone point me to the right place for me to understand what I need to do? In the end, I want to do is connect a Grove GPIO twig (such as Seeed’s chainable RGB LED) to the right-hand-side Grove port.

Thanks.

Did you ever get a response or figure out how to do it. Found this page but it is completely broken: https://community.seeedstudio.com/How-to-use-the-Grove-UART-port-as-a-GPIO-on-BBG-p-365.html

Thanks!