I understand your dilemma.
The column header is added in the AddColumn method. In the example program this occurs in Add-List-Header section.when statement:
EVALUATE Call-Function
WHEN "ADD-HEADER"
PERFORM Add-List-Header
is executed
The code in this paragraph will return a ListViewHeaderItem object which is actually used to set the Header text. Look in the same docs for ListViewHederItem to see what methods it supports.