Opdycke's Brigade arrived at Springhill first, and went into line of battle east of the road, facing east. Lane's brigade arrived shortly thereafter, and together repulsed a cavalry attack. Lane then apparently withdrew to a line behind and to the right of Opdycke, still facing east.
The third brigade was posted to the south of Lane, with a gap between its right and Lane's left. This brigade had a large number of new soldiers who were poorly trained. This brigade was attacked and driven back, with most of the pressure on it from its right.

The reports are a little conflicting as to how many regiments were in Lane's primary line of battle. The division commander's report says he ordered Lane to change front with two of his regiments, but Lane seems to indicate that it was with his entire line. In any event, Lane changed a portion of his front, whether it was only two regiments are more than two, I cannot tell. This was done to resist the CS advance that had routed the 3rd Brigade.

The right most regiment would have changed its facing from east to southeast, and once established the other regiments would have then come up on to the same line. Look at "Change of Front" at http://www.usregulars.com/csb14.html#_Toc83141984 Look at Number 743 et seq - there are even two or three diagrams that help visually. Although this applies to a single battalion, it would have been the manner that all of the regiments would have come onto the new line.

Let me know if this has helped, or if I have caused more confusion.