[ubuntu] Installing Ubuntu ON Ubuntu from LIVE CD from exsisting partition on HDD

Awhile back I installed Ubuntu 12.04 on my Macbook 1.1. It runs fine and all, but the system has gotten cluttered and I had poor protocols in place at the time so I'd like to go through with a fresh install of 12.04

CURVE BALL

It is a mac with no rEFIT, aka no usb booting
also the CD drive doesn't work :)

So i've been attempting to perform the fresh install by following the instructions on this page (https://help.ubuntu.com/community/Installation).
Everything goes according to plan until I get down to the installation step. I can confirm the files are moving over to the new partition, and the grub is updating. The issue arises after I reboot the macbook and go to grub menu to choose the new "install" and it doesn't appear. I can always boot back into my old install, but the new partition will not appear.

Has anyone ever attempted this? Any luck with it? Just looking for some help or guides specific to performing this process on a macbook if anyone knows of any.

Thanks
Linx