I found help in these two articles:
http://www.pendrivelinux.com/how-to-create-a-larger-casper-rw-loop-file/
which shows how to resize an existing casper-rw file, up to a limit of 4GB,
and:
http://www.pendrivelinux.com/create-a-larger-than-4gb-casper-partition/
which shows how to use a separate partition rather than a file to persist
changes.
I tried the latter first, and found that the live USB recognized the
partition with no problems. I am now trying to transfer my changes from my
old file-based casper-rw to the partion with dd (I hope it works...)
HTH,
