Here's my unofficial update for the flash writer that I decided to release now because it's been sitting on my HDD for months and I know it will get lost eventually.
Added HFW check
Added minimum firmware version check
Added patch file hash check
Added patch stack frame check (commented out of the official version for some reason)
Patch file is downloaded to the PS3's HDD from the web server instead of read from USB
Both the patch operation and the patch file has not been modified from the official version. This has been tested and confirmed working by myself and others.
Thanks to the PS3Xploit team for their flash writer tools & JS framework.