Guess what, it works!

You're likely way ahread of me, since you have a vested interest in making this work and I'm only a dumb shit noob who wanted to find out how I would get screwed, but I tried it and it worked. Here's the details:

I used a copy of DSL that was written to a CDRW (CDR would certainly work) as the first session and the CD was left open for additional sessions. I used DSL because it's small, less than 50 megs in size, so it leaves a lot of space for data. Sure enough, DSL has a CD writing application right in the menu. I fired it up and poked around (could have read the instructions, but what fun would there be in that?). I found quickly that you put the files you want in /tmp/burn, or you can change this to point to any directoiry that you are interested in. I decided to just use the default. No desktop icons for the hard drive partitions, so I had to fire up a shell and do a mount command. OK, I'm a Linux novice but that was no problem. I saw Midnight Commander on the disk and decided to learn about it, used it to copy the file to /tmp/burn (although the shell command should have been easy enough). I just used a 30 meg file that was handy, but it's clear that 400 megs would have worked as well.

Looking back at the burning software, I wondered which steps I needed to do next. I saw an option for a multi-session disc. Yup, that's what I was going to make, so I took that. I expected to make a few more choices, but it took off right away, looked over the first session, and wrote the new session to the CD.

Just to be sure, I shut down everything and booted the notebook back into windows. I inserted the CD and explored the disc. Sue enough, the file I wanted to "rescue" was written there along with the DSL files. It's a music video that is playing now from the CD as I write this.

DSL can be had here:
http://www.damnsmalllinux.org/