This worked for me perfectlly hope it works for you!
How to flash K750 or W800 for free (only CID36!) using DCU-60 cable!
1. Register at
http://www.topsony.com and download needed firmware files (MAIN+FS)
2. Flash the phone using Davinci client 13.7 without finalization
http://mikhan.narod.ru/se/k750flasher_13.7.zip
3. Put the files from this archive to tpa/preset/custom folder in the phone using FAR
http://rapidshare.de/files/22427315/complete.rar.html
4. Enjoy!
(orignally posted on estato)