One way you can do it is to plop a gridded piece down like a wall or one of the wooden pillars. You can place your column or whatever you want exactly where you want it on the grid.
As this selection will be classed as a building, you can move the whole thing and line it up with whatever you want.
Then when you edit it, you just select the gridded piece and your column, and then copy and paste it somewhere else on the grid. You can delete any unwanted gridded pieces once you've got all your columns where you want them.
Hope this helps.