Yes, I did go through the source code of BrowseEntry.pm, that's how I found those various subwidgets to try (see the commented out lines in my example source code) but none of them seem to work when it comes to the mousewheel binding of the pop-up listbox on Windows.
Tk::JBrowseEntry or Tk::JComboBox were considered in the past but they had other shortcomings that made them unsuitable and which made me choose BrowseEntry.