The first generation of Line6 MIDI Mobilizer uses a proprietary system that only works for apps specifically built to support it. Unfortunately, Lemur does not include support for this interface. The second generation, Line6 MIDI Mobilizer II supports CoreMIDI. You can use this hardware interface with Lemur. Please note that both generations of MIDI Mobilizer look extremely similar, they are differentiated only by the numerals II on the second generation.
More information is available on the Line6 website: