MakeBilateralCells.m in the directory
This package has been around since Version 4.
Haven't checked/test all features, but the basic functions seems to work with Version 8.0.4.
pastes a template that you can edit:
Open another notebook (Untitled-5 on the left in the screenshot) and evaluate an expression (say
In your input notebook (Untitled-4 in my example), evaluate
to get the list of open notebooks:
Your screen now looks like:
Select the first cell group in the target notebook. Go back to the input notebook and evaluate the folowing:
The fist cell group in the target notebook now becomes: