Okay, so thanks to about six different pages (being a new user, I can't post more than two links, so I've posted the two most useful), I've got this going. By running
gksudo gedit /etc/X11/xorg.conf in the terminal (Ctrl-Alt-T) to edit X11's xorg.conf file, then pasting the following in at the bottom:
Identifier "Mouse Remap"
MatchProduct "Saitek Cyborg R.A.T.5 Mouse"
#May also be "Mad Catz Mad Catz R.A.T.5 Mouse" depending on production date.
Option "AccelerationProfile" "1"
Option "ConstantDeceleration" "5"
Option "ButtonMapping" "1 2 3 4 5 6 7 8 9 10 11 12 0 0 0"
Option "ZAxisMapping" "4 5 6 7"
You should change the MatchProduct field to match your own version of the R.A.T. mouse. You can find it with
A few things to note if you want to understand what this block of text means are the
AccelerationProfile 1 sets mouse acceleration off. It's a personal preference thing-- you can omit this line if you like acceleration, or make it a higher number for a few different kinds of acceleration. You can read more about it in the first of the links below.
ConstantDeceleration is also not necessary, but it really helps slow the mouse down so you can use a higher DPS (because why use 1600 when you can use 5600?) without having your mouse fly all over the screen. Play with this number if you don't think it feels right-- higher numbers mean a slower mouse.
ButtonMapping is where the actual fix takes place: you'll notice that where one would expect the numbers 13, 14, and 15, there are 0s. This is because the three mode buttons are mapped to 13, 14, and 15. We want to stop Ubuntu listening to those buttons, so we un-map them with 0s.
ZAxisMapping is to get the back and forward thumb buttons working like they should. I honestly didn't do any reading about this one, I just saw one guy saying it should work, so I tried it and it worked. It's particularly mystifying to me since the back and forward thumb buttons are actually buttons 8 and 9, but if it ain't broke don't fix it, right?