Connect an audio cable from the MiniBrute audio out to your UX2 instrument audio input.
That's how you get any electronic instrument's audio into your computer through an USB audio interface like the Line 6 UX2.
Then, to send/receive MIDI notes to/from the MiniBrute, you'll use its own USB cable to get its (USB) MIDI ports available in your computer.
So, with Live, you're use a MIDI track to send/receive MIDI from the MiniBrute while using an Audio track to listen/record the Line 6 UX2 audio inputs.
For lower latency results, use the Line 6 ASIO driver when choosing the audio interface to use in Ableton Live.