I'm using mscomctl.ocx from vb6 sp5.  As per the Platform SDK documentation,
under LVM_SETCOLUMNWIDTH

        lResult = SendMessage(               // returns LRESULT in lResult
        (HWND) hWndControl,                  // handle to destination
control
        (UINT) LVM_SETCOLUMNWIDTH,           // message ID
        (WPARAM) wParam,                     // = (WPARAM) (int) iCol
        (LPARAM) lParam                      // = (LPARAM) MAKELPARAM ((int)
cx, 0)
        );

iCol
Zero-based index of a valid column. For list-view mode, this parameter must
be set to zero.
Return Value
Returns TRUE if successful, or FALSE otherwise.
This references the commctrl.h header file which I used to get the constants
to import into my project.
Code fragment:

Private Function SetColumnWidth(lNewTwipWidth) As Long

Const LVM_FIRST = &H1000
Const LVM_GETCOLUMNWIDTH = LVM_FIRST + 29
Const LVM_SETCOLUMNWIDTH = LVM_FIRST + 30

Dim lNewPixelWidth

lNewPixelWidth = lNewTwipWidth / (Screen.TwipsPerPixelX)
SetColumnWidth = SendMessage(ListView1.hwnd, LVM_SETCOLUMNWIDTH, 0,
lNewPixelWidth)

End Function

This does in fact return 1 indicating success.  Unfortunately when I call
this it blanks out the ListView control so that nothing is displayed in it.
All the data is there - I can retrieve, set, add ListItem entries etc, but
nothing displays :-(  I tried doing a .Refresh thinking I just needed a
Paint, but that didn't help.  Any ideas?

Thanks!