I want to boot my computer using a stock fedora livecd, and then use livecd-creator to roll a new custom livecd. I want to do this while never having modified that computers internal hard drive, though I have an external usb drive I can temporarily plug in for scratch space. Doing this today may be possible, but is difficult. I created my kickstart file with system-config-kickstart using the livecd, I didn't see options for temp/cache directories with livecd-creator, so I tried with Revisor which had those options in it's interface/config - but it wrote the rpm's out to my scratch space as I asked, but then didn't install where I asked it to and instead filled up my /var and crashed the system (OOM). (In reality, I have a computer with no internal hard drive, which I want to run entirely from an SD card made from a custom livecd, optionally attaching my usb drive if I need persistent storage. I can easily transport all my software from work to home or anywhere else on a tiny SD card, and don't have to worry about an HD dying). This feature would be good for Windows or other users who would like a customized livecd without having to alter their OS though, or in places like work where they might not be able/allowed to. I don't mind if my scratch space needs to be formatted ext3 or whatever, but it might also be nice to support all scratch space needs using a temp file on a local or external fat or ntfs file.
livecd-creator now has a tmpdir option (--tmpdir=/path/to/tmpdir) which gets you 98% of the way there. The other 2% is that the output goes into the current working directory, so you have to be in a directory that has the space.
Excellent, I will give that a try! Thanks!