You will need to use a WebListBoxStyleRenderer,
Public Function StyleWrapWhite(s as string) As WebListBoxStyleRenderer
var style as New WebStyle
style.value(“white-space”) = “normal”
style.value(“word-wrap”) = “break-word”
style.BackgroundColor = color.White
var cellrenderer as New WebListBoxStyleRenderer(style,s)
return cellrenderer
End Function