This is based on this post in the Galaxy Gear General forum:
I have a Sprint Galaxy S3, rooted stock MK3 with the hotspot mod flashed.
TS is running EnSec Patch & Imperium Operative Installer 20140221, option 2.
This is all from memory, but should be mostly accurate.
1) Enabled Xposed module and restart TS.
2) Installed HackConnectivityService.apk (found in referenced message). Enabled and TS restarted.
3) On phone, installed FoxFi (Sprint/AT&T only)
4) On TS, installed PdaNet(Tablet)
5) On phone, start FoxFi and run through configuation. Don't remember what I did here, but I don't think it was anything unusual.
6) On TS, go to Hack ConnectivityService app. Make sure the hack is activated and choose WiFi. Mobile may also work but I haven't played with that option too much.
7) Start PdaNet(Tablet). Choose configure. Start scanning.
8) Back on phone, Activate Bluetooth Mode. It ask if you want to be visible for 120 seconds. Choose Yes.
9) Back on TS, you should be able to pair with the phone's FoxFi. Click on bottom grey button. It may say Connect, but I can't tell because the screen is too small!
10) You should get a connected screen.
That's the general idea.
Without the Hack Connectivity Service in place, I could only browse the web. By choosing "WiFi" in enables Play Store access and GMail syncing, etc.
Other than the usual TS being unable to maintain a stable BT connection for any period of time, I have only found one other problem. GMail won't automatically sync for me over this connection. I can open GMail and manually check for new and it works fine. Maybe a Tasker script would help.