file=/dev/sdb1/preseed/ubuntu.seed should be file=/dev/sdb1/preseed/mint.seed
It would've been a great catch.. but like I said, that's what I used for Daryna. For Elyssa (although I failed to mention it), I did use file=/dev/sdb1/preseed/mint.seed, yet it didn't work.
In fact when I later thought about it, I was even surprised that /dev/sdb1/preseed/ubunto.seed worked, because I don't see how that could be a valid path under any circumstance. /dev/sdb1 would first have to be mounted for the filesystem to be accessible. I'm thinking the file= argument was ignored..
Well I did mount the CD (mount -o loop LinuxMint-5-r1.iso /mnt/temp) in order to copy the contents of it to my hard disk. Or did you mean mounting from busybox? In busybox I can mount the hard disk with the contents of the CD, but I'd have to dive into the scripts in order to figure out how to get them to use that. Oddly, I can't mount the USB key from busybox.