If you put Painters tape on the floor straight in line with the shot line put your right toe's along the edge of the tape, without moving you right foot step toward the table and to the left with your left foot with the toes of you left foot point toward the table, now bend over and place you bridge hand on the table.
This advice does not address the issue. The issue is that if you are going to start out by squarely straddling the shot line, directly looking down the line (as Mark advocates) - which means having one foot on each side of the shot line - then you must move your right foot (I’m assuming a right handed player) over to the left side of the shot line (painter’s tape) in order to end up where Mark wants you to be. Call it a dance step or something else, you have to move that right foot.
Watching the pros, including Allison Fisher, I don’t see them moving the right foot (and therefore, necessarily, their entire body) the way Mark says it must be done. This leads me to conclude that the better way to proceed is to do whatever shot line assessment you want - including standing behind the shot line, straddling it - but make your final upright position one from which you can drop down without moving your right foot (or without moving more than a very small distance - certainly less than you would consider to be the dance step).
I appreciate the feedback from some that putting the toes of the right foot against the shot line is not critical. The goals here are to be on the shot line when you get down on the shot, and to have sufficient clearance to swing the cue. I’m thinking that “sufficient” (my word) should probably be replaced by “just enough.” The less you have to place your body to the side of the shot line, the better.