Greetz
While it's true and desirable to see the kernel messages while loading, I take some issue with using Gentoo to accomplish this, unless you're quite familiar with Linux as well as all your hardware. Then there's the kernel differences that may result in not telling you anything useful about Ubuntu, which is what I assume you'd like to end up with. Also it could be you already have the tools you need and if not there are simpler ways
First off, the Live portion of Ubuntu does boot, right? If that's true then you already have that exact kernel's messages even though the st00pid splash screen hid it during boot. The first thing to do then is to launch a terminal and type "dmesg |tail". This will give you just the tail end of the boot logs and often that's enough as Linux will try to solve problem issues for awhile before it gives up.
If that is too small a sample then you'll have to type "dmesg |more". (Aside- one cool thing you can do to avoid duplicating typing is hit the up and down arrow keys which will cycle through command history and when the previous "dmesg" command pops up just backspace out "tail" and insert "more") Anyway "|more" will just display one screens worth and prompt you to notch through by the line or by the page (space bar). This works in any console. If you're in X you can omit the "}more" and just use the scroll bar.
Until we see that information the best I can offer right now is to try some LiveCDs to see what boots and what hangs. Puppy, Slax, and Knoppix are good choices for reasonably different kernels and load levels.
It sux you're having so much difficulty especially on a new and pretty sweet sounding system. We will work it out though, ultimately, since you show determination and perseverity and that attracts helpers. Nobody enjoys helping lazy whiners, and you're not that.