Wanting to build or put together a mill column

Guys and gals I’m very new to machining but absolutely know my way around metal fabrication/welding and not scared to take on any task as my mind for some reason does see anything as too big to take on.

I’ve read through threads about converting round to square column on a mill and was wondering,as I am very knew to all of of this, how would you control it both powered and manually (I will insert a pic of dovetail slide) Even ways to manually controll it? I found this dovetail slide 6” wide with I believe 19” of travel and I want to use it but not sure what I would need and how to set it up? Or if there are heavy duty, somewhat mini mill column assemblies that can be purchased im good with that , as long as I don’t have to sell my neighbors car to pay for it.lol. Any help is appreciated.