What's the trick to add some code in a method at run time?

For example, I have a grid class that I use at different locations. By default the columncount is -1. At run time, the columncount will change to something else and by that, this will create the columns. Since the columns will only be created at that point, I can't insert some code in these methods at the design class level, I have to insert it at run time, or is there a better way to do it?

Thanks.