On MacBookPro 8,2, installing 14.04 (Trusty Tahr) is so similar to installing Ubuntu 13.10 (Saucy Salamander) on MacBookPro 11,1 that I am simply linking to that page: https://help.ubuntu.com/community/MacBookPro11-1/Saucy
""Note!"" You need to edit the boot options for this particular model so that the right display settings are in effect, otherwise you may just see a blank screen after choosing "Try Ubuntu"
I think you can do this without using rEFInd as suggested in the link below, just follow the steps that configure the boot settings for the display.
See the boot settings here: http://ubuntuforums.org/archive/index.php/t-2157775.html
The only difference is that speakers work out of box on 14.04, but not on 13.10.
You can find out the model identifider in MacOS by following http://support.apple.com/kb/ht4132 or in Linux by typing at the terminal:
sudo dmidecode -s system-product-name
The open source Broadcom wireless card driver does not work on MacBook Pro 8,2. For that you should connect your MacBook on the Internet in wired connection, and after installing Ubuntu 14:04, run the following command to install the Broadcom firmware:
sudo apt-get install firmware-b43-installer
More information: http://wireless.kernel.org/en/users/Drivers/b43#devicefirmware