Well ... I did make a bootable 64-bit paintitblack stick just now. Unfortunately, the only computer in my house that will boot it to the desktop has a broken ethernet chip and needs the Broadcom firmware to run wifi, so I can't post from that one (without doing more work). This release has a "EHCI-orion module not found" problem that dumps my 64-bit desktop systems to a busybox prompt.
Here is all you need to do ("x" is YOUR device ID and don't get it wrong!):
dd if=/dev/zero of=/dev/sdx bs=512 count=1
Then from the KDE desktop "kdesu gparted" and make an ext2 or fat32 partition, and mark it bootable.
Pull the stick and reinsert it, and use your dolphin or whatever file manager to mount it to /media.
Alt-F2 "kdesu unetbootin", choose your ISO file, choose your /dev/sdx stick, and it works. Even on a junky old plastic Verbatim stick with a proprietary hidden partition on it.