You can print a jig to mount it on the toolhead.
https://makerworld.com/en/search/models?keyword=dial+indicator+h2d
You don’t have to “zero” it. You can simply start from mounting it on to the toolhead, then raise your bed carefully until it barely touches the indicator (also shows a reading on the indicator).
Then you can adjust the gauge/markings on the indicator to zero it. Many indicators feature a rotatable gauge which can zero dynamically. If yours can’t do that you need to note down the zero position then do some math yourself 
After that you can start manual tramming. Power off the printer. I use the 4 visual markers (square markings on the bed) as where to probe. Then I try to make the 4 probe spots show a same reading, as far as I can get.