Separate listboxes is awkward because I lose the horizontal scrolling capability
provided with the listbox.

I've been trying something though.
I've created textboxes above the listbox.
I then populate  the textboxes with the column  headings.
Now, when I scroll to the right, I have to determine which columns are currently
displayed and update the names in the textboxes.

Not sure if it's going to work, but I'm giving it a shot.