I use the side scrolling without the use of btnx with the xorg-server-1.5.3 release, using "evdev" and "hal" (gentoo linux).
I guess that latest ubuntu should take care of that nicely ?
btnx has been stopped and is no more supported though.
Note that lomoco (LOgitech MOuse COntrol) don't recognize the MX1100 (or, at least, didn't work for me 6 months ago, but that has perhaps changed ?). Is this project sill alive, that'll be a good question.
Note that I still use the AA cells found in the box with the mouse. The power management of this mouse is really impressive !
I'm not sure if the lomoco project is still going. I had to download the source for it and add in USB device IDs for both my MX518 and my MX Revolution. I ran into some weird runtime behavior with libusb2, so I didn't really push too hard into using the project... If I get bored in the future, I'll probably pick it up again and see if I can figure out what was going wrong.