It didn’t work for me the first time (was stuck at the preparing for install screen), so I guess the order of the rEFInd and partition are important. Reference.
I use a Macbook Alu (late 2008) with clean fresh install of Yosemite.
Step 1
Download Ubuntu for Mac. I used ubuntu-14.04.2-desktop-amd64+mac.iso.
Make boot drive of Ubuntu. The instructions using dd command didn’t work for me. Probably because I use a partitioned harddrive instead of a USB stick? Anyways, I ended up burning the iso file instead. The instructions from Ubuntu works well.
Step 2
Install rEFInd. Basically download the file (I used refind-bin-0.8.7) and run the install.sh script.
Shut down the computer and power on again, you should see the different boot screen.
Step 3
Make the partition of the OS X smaller to make space for Ubuntu with Disk Utility. Do not make a new partition (I did it the first time, may be this was the problem).
Step 4
Restart and boot to the Ubuntu DVD. Choose Install Ubuntu alongside Mac OS X. And I had no problem booting into Ubuntu, except… my Wi-Fi is not working.