How can I create a temporary filesystem on an NTFS drive using Ubuntu Linux LiveCD? I would like to make a temporary filesystem in a file, like a .dmg or .iso that I can mount and modify files on, on top of the NTFS drive. Basically, I want to use the space of the NTFS drive without repartitioning, but need particularly the executable bit to be set properly on files, which NTFS does not provide. I only need it to be about 500MB. I don't care if it can be read from Windows, I'm probably going to delete at the end of my session anyway.
To explain my situation more fully, I am running Ubuntu from the LiveCD, which runs in RAM. Depending on the computer, so the main filesystem at '/' only has 1-4G, depending on the computer hardware.