after two weeks of trying, I'm still struggling to install Ubuntu 12.04.


In brief:

Machine: Apple macbook pro 5,1 which i've recently upgraded to Mac OSX 10.8.1 Mountain Lion, after upgrading the internal HDD.

The optical disc is damaged or for whatever random reason, consistently spits out failed discs while reading or writing. So am not replacing that. Hence i've taken the route of trying to install 12.04 using a usb-stick and/or from a separate partition on my hdd.

For this, i spent about 7 days researching into all issues. The two best methods are mentioned here:
http://forums.macrumors.com/showthread.php?t=1329407

and

http://cweiske.de/tagebuch/ubuntu-on-macbook-air.htm

Note: none of these are specific to my MacBook Pro 5,1 but the concepts are applicable.

My status:

1. Used gparted to add dos partition tables to a usb-stick.

2. Used Unetbootin to install the mac-alternative.iso of 12.04 to the usb-stick.

3. Created several partitions on my mac hdd, and in the fourth partition, used the powerful 'dd' command to install the image on the usb-stick to the internal hdd. at this stage, the first problem occured, my terminal just hung, the image was copied.

4. restarted and synced rEFIT, which i installed a few days earlier, prior to installing ubuntu.

4.Clicking on the 'tux' option in rEFIT i got the unetbootin option, but instead of booting a live version it just went into installing. So i did. it went through the steps, but showed errors while installing software apps, so had to skip that step, and also failed to install grub.

5. on the restart, the tux logo shows up next to the mac os logo. clicking on it just leads to a black screen.

6. holding down the option key, and rebooting, i get the boot from 'legacy OS' option. clicking on that i seem to get into loading, but the 'missing operating system' error pops up immediately.

for sure, apple has made it extremely tough and challenging to install linux on their laptops.
i've never experienced so much suffering in trying to install linux in the 14 years i've used it.

the documentation on the ubuntu site also has nothing on how to install on the macbookpro 5,1 without an optical disc. Actually, am still eagerly looking forward to the documentation on how to install Ubuntu 12.04 on MacBookpro 5,1 on the official documentation wiki.

Frustrated.

I'm willing to start again, but could you please guide me what steps to use?
Thanks for your help.

Regards
Niyam