I have this same mouse, and I wanted to bind the two buttons on the side of the mouse to forward and back. Here is how I solved this:
1) Use the utility "xev" to determine what numbers the buttons you are wanting to remap correspond to. You may have to install this package using
sudo apt-get install xev
Once xev is installed type "xev" into a terminal, and an X window that is white with a black box will pop up. Moving your mouse into that window will begin registering events to the terminal. Reading the output of that carefully will tell you the numbers of your mouse buttons. On my mouse, the left and right tilt map to buttons 6 and 7 respectively.
2) Now we are going to use the utility "xbindkeys" to remap the mouse buttons to key presses. If you don't already have this installed you may have to install it with
sudo apt-get install xbindkeys
3) Create a file in your home directory called ".xbindkeysrc". This is what xbindkeys will read to see what you are remapping. The contents of my .xbindkeysrc file are:
"/usr/bin/xvkbd -xsendevent -text "\[Alt_L]\[Left]""
m:0x0 + b:8
"/usr/bin/xvkbd -xsendevent -text "\[Alt_L]\[Right]""
m:0x0 + b:9
So this tells my computer to send the keyboard button presses "Alt+Left" or "Alt+Right" to the system using the virtual keyboard (xvkbd) whenever button 8 on mouse 0 is pressed or button 9 on mouse 0 is pressed respectively. These keys correspond to the the forward and back keys in most applications. This will work, for example, in Nautilus, chrome/