Making a "writable" livecd?

[peaceful]

I successfully created a working livecd by following the livecd howto wiki page at:

http://gentoo-wiki.com/HOWTO_build_a_LiveCD_from_scratch

The problem is that I would really like the booted system to be writable (on a ramdisk, not on the cd itself), like it is on the gentoo installation livecd's. I figure there must be some standard method of copying the whole system onto a ramdisk. Can anyone point me in the right direction for that?

[yabbadabbadont]

I think what you need to be looking for is Unionfs. I believe that it is what allows for "writable" live CDs.
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