This post from Patrick is very useful when trying to identify the column ID of the tabular form. But when column order has been moved up/down or some are marked not shown, the column ID might be difficult to determine.
This simple technique of using Javascript event on the Element Attributes of the needed columns can be used to quickly identify the column ID.
onmouseover="alert(this.id);"
You can definitely choose a different event that fits your situation.
See sample here.