Install https://github.com/doronz88/pymobiledevice3.
Get your device's UUID:
xcrun xctrace list devices
Mount the disk image:
sudo pymobiledevice3 mounter auto-mount
Start the tunnel:
sudo pymobiledevice3 remote start-tunnel --script-mode
Keep the tunnel running. Open the app you are trying to enable JIT on your device. Keep the screen alive.
Now, paste the output of that command as the RSD connection to start a debug server:
sudo pymobiledevice3 developer debugserver start-server --rsd <YOUR_CONNECTION_DETAILS>
Get the PID:
sudo pymobiledevice3 processes pgrep <YOUR_APP_NAME> --udid <YOUR_UUID>
Open lldb to start debugging:
lldb
Run the following commands:
(lldb) platform select remote-ios
(lldb) process connect connect://<YOUR_CONNECTION_DETAILS>
(lldb) settings set target.memory-module-load-level minimal
(lldb) attach -p <YOUR_PID>
(lldb) detach
(lldb) exit
If you're using AltStore you can just make sure you install the dependencies to the Python install that Xcode uses: