I would use a minor variation of the script above where I use symbolic links for the flash software instead of actually copying it to the unionfs. saves memory / diskspace in ram disk.

mkdir /UNIONFS/usr/lib/win32
ln -s /mnt/sda1/essential-20050412/* /UNIONFS/usr/lib/win32
ln -s /mnt/sda1/RealPlayer8/realplay /home/root/Desktop/RealPlayer8
mkdir /home/knoppix/.mozilla/plugins
ln -s /mnt/sda1/flash/flashplayer.xpt /UNIONFS/usr/lib/mozilla-firefox/plugins/
ln -s /mnt/sda1/flash/libflashplayer.so /UNIONFS/usr/lib/mozilla-firefox/plugins/

i use a klik .cmg to run realplayer gold on the rare occasions that i need it, but the same logic would apply if you wanted to keep an installed copy in a directory on a thumb (or other) drive.