Have you tried UNetBootin? I really like it, and it's worked well for me in the past. If it doesn't work, you could try Fedora's LiveUSB-Creator. And I'm guessing that, if you could boot successfully from the flash drive, there'd be no problems using the built-in installer. Finally, it may be possible to copy the contents of the *.iso directly to the flash drive via dd like this:
dd if=/path/to/opensuse.iso of=/dev/sda1
where "/dev/sda1" is the flash drive's device name. Please also note that the flash drive must be unmounted (but not ejected) for this last option to work. To be honest, though, I'm not sure how stable this last method is, so I'd really recommend UNetBootin or the LiveUSB-Creator. Good luck!