Originally posted on a Chinese forum, XDA forum member yhd4711499 has posted the tutorial on how to jailbreak your Omnia 7 running Mango.
If you have updated to Mango, you’ll need to roll back to 7932 or earlier and make sure your device is unlocked. The XDA member has posted the 4 files that you will need and step by step instructions.
Before updating to Mango, you’ll need to copy the lanuguage and unlock xml files and deploy the Wp7RootTools o.5 alpha.xap, renaming the xml files to the original names. You’ll then enter a few codes, and then update to Mango.
After updating to Mango, enter Diagnosis, GPRS settings, choose the unlock xml file and save. No rebooting is required, and you should be jailbroken!
For detailed instructions and to download the required files, head on over to the forum thread._________