Just to amplify what David has said, there were a number of options.
If, as per your scenario, they were in column of fours (unlikely), and definitely wanted to be in line, and there was no immediate enemy threat, and were marching "by the right" (ie Grenadier company leading) then they could wheel the head of the column off the road to the left across the fields and then wheel back to the right (ie covering two sides of a triangle, to end up in a column facing right, then simply wheel each of the fours back into line. If they wheeled directly to the left (ie marched straight to the crossroads then wheeled left, halted then wheeled the "fours" back into line they would be inverted and would need to countermarch to correct this.
As David says, it is however unlikely that they would march down a wide road in a narrow column of fours. As they approached the rear of the battlefield they could theoretically extend their front by doubling into "eights" (approximate quarter companies), then "sixteens" (approximate half companies) before forming a tactical column of companies. It is however much more likely that they would stop whilst still a little distance behind Quatre Bras, wheel the non tactical column of route ("fours" or "eights") back into line, then wheel back into a column of equalised companies which would then close to quarter distance. These could march onto the battlefield in that formation, ready to form line by deploying to their front on the head of the column or, if the tactical situation required, rapidly form square. Mike Robinson's new book "The Battle of Quatre Bras" clearly has Picton's Division halting north of Quarte Bras and re-forming before moving on to the battlefield itself.