OS X install Mint on external HDD

[LRRP]

I have an iMac (8,1) with OS X Lion, Windows 7 in Bootcamp and have installed Mint onto an external (120g) firewire drive using a liveDVD. I manually partitioned the external with EXT4 file systems on the root, boot and home partitions. At this point everything worked fine. After rebooting the only way I can get back into Mint is by booting off the liveDVD. In the OS X disk utility I can see the external drive but the four partitions are grayed out (not mounted?). I assume that the problem lies with the EXT4 file systems, which OS X cannot recognize. Grub is installed on the external drive and using rEFIt on the Mac. I do not wish to disturb the Mac install. Windows and Mint can be deleted/reinstalled without a problem. I have considered deleting Bootcamp and doing a manual partition of all drives. Hardware wise I have an internal 320g HDD, a 1tb external (half forTime Machine backup, half for data) and the 120g with Mint installed. I would like to have some sort of bootloader on Mac OS X which could point to Mint and Windows in their own partition(s). I don't particularly want to partition the internal drive for all three operating systems.
Oh, virtual installs are not an option. (VMWare Fusion and Parallels are sitting on my bookshelf gathering dust) Any recommendations would be appreciated. Thanks in advance.

[ugajin]

I tested rEFInd (upgrade fork of rEFIt) as well as the alt key method to boot Mint from a partioned HD (see http://forums.linuxmint.com/viewtopic.php?f=46&t=123458. Have you tried 'alt' key boot? No idea if it will work, but I would like to know, as I am interested in running Mint from an external bootable drive.

[usbtux]

I'm not a mac user but did you set the bootloader to the ext hdd? in windows that's what you do then from the bios or boot manager choose the hdd to boot

http://youtu.be/gVCfeFOxGLQ External install

If that wont work use plop bootmanager on a cd - boot to the cd then chose the mint install from there.

[LRRP]

Thanks for the suggestions. I have tried Boot Managers such as rEFIt and rEFInd. They will display Tux as an option when booting on the Mac. Unfortunately selecting Tux only gets me a black screen telling me that I have no operating system installed. I think it may be possible to install grub or Plop (some sort of bootloader) on a USB Flash drive whose purpose it to chainboot the Linux Mint install. I have also been working on putting the Linux /boot partition onto the internal HDD. Many hours of experimentation have yielded only frustration.
To usbtux: I have looked at Plop but it is a Windows program. It may be useful if I can adapt it.
I do not wish to install Linux entirely on the internal HDD, I don't want to use virtualization (Fusion, Parallels, etc.), I don't want to use liveCD. That said, putting a boot partition on the internal HDD or booting from a USB flash drive is acceptable.

[LRRP]

Solution found (partially)!

After weeks of trying numerous configurations, including 3 OS X reinstalls, and 2 recoveries from backup, I have hit upon an acceptable (to me) solution. Mac OS X internal drive has a couple of hidden partitions which require consideration. At the beginning of the drive is the "EFI" or bootloader partition and, I think, at the end is the Recovery Partition, with the OS stuck in between. Point being, be careful when partitioning. I attempted to partition using Boot Camp Assistant so that OS X would take care of these hidden partitions. Unfortunately it didn't work so I ran the LinuxMint install and manually partitioned the internal drive.

I created a small (500mb) Linuxmint /boot partition on the internal disk. The remainder of the install went on the external hdd. Grub bootloader was pointed at /dev/sda and found it's way to the /boot partition. Voila! Using rEFIt the Linuxmint install boots properly every time.

My primary reason for seeking an external hdd install was to save space on my 320gb internal drive. I didn't completely accomplish this but I only used less than 1% of the internal for the boot partition. Unfortunately I messed up the Recovery Partition on OS X, so I created Recovery on a usb flash drive. I can live with that.