If you want to rescue your install, but bypass your kernel loading and
use the stock one, you can type:
rescue root=/dev/hdaX video=vga16:off
at the prompt instead of just hitting ENTER. This will use the stock kernel on the disc to boot up your install, if it's rescue-able. (Don't forget the video option!)
If you don't even want your filesystem mounted (in order to convert it to ext3, or something) you can hit ENTER at the first screen (loads the image `linux'), and then when the big blue welcome screen pops up, switch to tty2 (CTRL+ALT+F2). This is a small shell, ash, without any big editors, and with only a few commands (to see which, as it says, do a `ls /sbin /usr/sbin` (and more; I forget)). Unfortunately for me, there is no loadkeys (I'm a Dvorak dork), but I discovered that if you mount your root filesystem and then chroot to it, you can `loadkeys dvorak` from there and the setting will persist even when you exit an unmount it.