Oh, woe is me. Because it can't be that hard, and I'm not normally this dumb, but its 4hrs and my head is hurting.

I've a 2009 Mac, currently running Mountain Lion, 10.8.2. My CD drive has long not been part of this world. I've already downloaded Ubuntu iso, partitioned my disk and installed rEFIt, but I can't seem to make a bootable USB image. I've been through the detailed instructions here:


but they don't work for me. And I'm no slouch with Bash or the command line. Still can't get any joy.
Every step of the procedure completes fine, but all I get when rebooting is 'missing operating system'.

Ah huh. I've already been down the sync partition tables route. Several times.

There must be loads of people that've been through this? The searches just keep taking me to the same useless pages, the one above and this one:


They don't help. Oh woe is me....