Yes, you have to install the Logitech software to get the high resolution mode - or you have to use a Linux where this is compiled in the kernel. Maybe someone can port this stuff to Windows.
In the meantime I've just checked with Spy++ that my Logitech M705 sends in high resolution mode WM_MOUSEWHEEL-messages with a delta value of 1 when I scroll slowly (which means it sends 120 messages instead of 1 at normal resolution for the same angle) and if I scroll faster the delta value grows up - I think the driver accumulates the delta to avoid a message overrun.
That results in the strange fact that I can adjust the volume level better when I scroll faster because it generates less messages.